The Election in Pictures

Some data updated through September 2.

Sunday, July 29th, marked the point when there are just 100 days left until the November midterm.  In this post I will try to pull together my various writings and predictions for both the 2018 House and Senate elections.  I begin with the most important factor that influences both types of races, the President’s job-approval figures.

Presidential Approval

The President’s job-approval rating is an important predictor of midterm election results in both my model for Senate elections and the one for House elections.  The Democratic advantage on the “generic-ballot” question about voting in House elections has waxed and waned as Donald Trump’s approval rating first fell after he was inaugurated then rose again over the past few months.

Donald Trump enters the 2018 election with about the same level of public support Barack Obama had in 2010. Though Obama was much more popular when he was inaugurated, that goodwill faded over the following eighteen months. In the 2010 midterm that followed, the Democrats were “shellacked,” losing sixty-three seats in the House of Representatives. Support for Trump also ebbed away during 2017, but he has rebounded slightly from his nadir last December.


Though Trump’s overall approval rating heading into the first midterm is largely identical to Obama’s, Trump is more intensely disliked.  Pew reported that the proportion of people saying they “strongly” disapproved of Obama’s performance in office grew from 18 percent in April, 2009, to 32 percent by September, 2010.  For Trump, CNN found that he took office with over forty percent of Americans already strongly disapproving, a figure that has remained relatively unchanged.  In its June, 2018, poll CNN reports a “strongly disapprove” figure of 45 percent.

The House of Representatives

As the first chart shows, the president’s job-approval rating bears directly on the “generic-ballot” question.  Based on polls through September 2nd, the Democrats’ lead on the generic ballot has grown slowly since Inauguration Day and inversely with Presidential job approval.  The grey area in the chart below represents the likely range of outcomes.  Since April, Donald Trump’s net approval rating has ranged from about -8 to -14.  Those values define the left and right sides of the shaded region.  When I include estimates of any methodological or unique “house effects,” I find that polls conducted over the Internet show a pro-Republican tilt of about 2.6 percent.  Gallup’s polling shows an ever greater Republican edge of nearly five percentage points.  I use the values for live polling, which are most favorable to Democrats, and those from the much-less favorable Gallup, to define the height of the grey area.

Notice that, according to these results, even if Trump were to achieve a net approval rating of zero, Democrats are still predicted in live polling to lead on the generic ballot by about six points on Election Day. That reflects the slow growth in support for Democratic House candidates over Trump’s presidency from about four points on Inauguration Day to a predicted six points this November. In past elections the margin of victory in generic-ballot polls has proven to be a pretty accurate predictor of the actual division of the vote.

An earlier version of this model showed a small, marginally significant positive boost for Democrats in polls of likely voters.  That difference has disappeared as the number of polls has increased.  Since Democrats are generally disfavored in likely-voter polls, especially ones conducted in midterm years, a finding of no difference between registered and likely voters is actually positive news for Democrats.

One other major problem for House Republicans has been the historically large number of their Members who are leaving, or have left, the House.  Forty Republicans will not be returning to the House next January creating an excess number of more vulnerable open seats on that side of the aisle.  Only 18 Democrats are leaving the chamber.  With 22 more retirements than the opposition, the largest midterm gap since the New Deal, the Republicans face a loss of 39 seats based on the historical relationship between the two measures.

The Senate

There is no national generic-ballot question for Senate elections because only two-thirds of the states have a Senate race in any given year.  Looking back historically over Senate elections, the fate of the President’s party depends directly on his job-approval rating and, unlike for House elections, the state of the economy as measured by the growth in real disposable personal income per capita.  Any plausible combination of approval for Donald Trump and income growth predicts that the Republicans will fail to win a majority of the popular vote for Senate in November.  One reason is that the popular vote for Senate candidates of the President’s party runs four points lower when the President is not on the ballot.


Much has been made of the 4.1 percent increase in Gross Domestic Product reported for the second quarter of the year.  That figure represents the growth in nominal GDP; after adjusting for inflation the figure is 2.8 percent. Unfortunately for the Republicans little of that growth appears to be “trickling down” to ordinary Americans.  Here are the recent trajectories for both real GDP and real per-capita disposable personal income.

Personal income has hovered around a two-percent growth rate for the last three quarters, while real GDP grew more quickly.  If voters respond to changes in the amount of money in their pockets, then the economy will not be sufficient to power the Republicans to victory in the fall.  From the chart above, a two-percent growth rate in per-capita income and even a 45 percent approval rating for Donald Trump still leaves Republican candidates short of a majority in the national popular vote for Senate.

From Votes to Seats: The House

Americans became much more cognizant of the word “gerrymander” after the redistricting that followed the publication of the 2010 Census.  Drawing lines for partisan advantage has become easier as voters have segregated themselves geographically by party.  Together the two forces have combined to create a Republican “bulwark” in the House. Democrats need to win the popular vote by more than fifty percent to take half the seats in the body.  How much more is subject to debate, but most estimates put the needed margin of victory in the range of six-to-eight percentage points, or an election where the Democrats win somewhere between 53 and 54 percent of the popular vote.

For instance, The Economist currently projects the Democrats to win 54.3 percent of the popular vote, or a margin of 8.6 percent, but take just 51.3 percent of the seats in the House.  Both Dave Wasserman at the Cook Political Report and Nate Cohn at the New York Times cite a seven-point margin as the minimum required for a slim Democratic win. My model agrees.  It uses historical voting data back to 1940 to estimate the relationship between seats and votes. I include adjustments for redistricting after each Census and for the decline in political competition since the 1994 “Contract with America” midterm. Using those data I estimate the Democrats need at least 53 percent of the national popular two-party vote to win a majority in the House of Representatives.

From Vote to Seats: The Senate

Unlike House districts, Senate seats cannot be gerrymandered because they constitute entire states.  That makes the Senate more competitive than the House.  There is no equivalent “bulwark” in the Senate; winning half the popular vote generally translates into about half the seats.  Since the model predicts that the Democrats will win a majority of the 2018 popular vote for Senate, we should expect the Democrats to win a majority of the 35 Senate seats at risk.  Winning 18 of those seats would not be enough to flip control of the Senate because of the Vice President’s tie-breaking vote.  Nineteen seats would give the Democrats control.


From Here to November

Can the Republicans rebound between now and election day?  Unfortunately, recent history suggests they will face even larger obstacles in November than they do todayPresidential approval generally declines as the election nears, and the opposition party’s advantage on the generic ballot grows.

Job approval for first-term presidents fell on average about five points between May/June and October of midterm election years.  Trump might see a smaller decay because his current popularity is historically low, around 42 percent.  Presidents whose approval was above fifty percent in May/June saw a 3.3 percent drop in approval; those who started below fifty percent in May/June saw their ratings fall an average of just 1.9 percent.


In off-year elections, generic ballot polls for both of Obama’s midterms fell as the election neared.  For George W. Bush in 2006, Republicans recovered slightly from their early summer deficit, then watched support for their candidates crater in October.  Most observers credit that sharp decline to the Mark Foley scandal that fall.

 

From Job Approval to the Ballot Box

“Generic-ballot” polls predict a nine or ten point Democratic victory in House elections this fall, enough to flip the chamber.

As most observers know, support for the Democrats on the so-called “generic-ballot” question has moved inversely to the public’s opinion about Donald Trump’s performance in office.


Can we use this link between support for the parties on the generic-ballot question and Trump’s job approval figures to forecast possible election results in November?

There are 228 generic-ballot polls in my current dataset covering the period from Inauguration Day, January 20, 2017, through June 9, 2018.  Of those 228 polls, 209 also collected data on presidential approval.  Those 209 polls constitute the sample for this analysis.

A weighted-least-squares model using my standard predictors — days in office, polling method, and polling sample — plus the net Trump job approval score “explains” about half the variance in the size of the Democrats’ lead on the generic-ballot question.  Overall, the Democrats’ lead has increased at a slow, but discernible pace since the Inauguration.  Even after taking Trump’s job approval into account, I find support for the Democrats grows about 0.3 percent every hundred days.  At that pace, the Democrats will have picked up about 2.2 percentage points by the time the election takes place on November 6th, some 655 days after Trump took office.

Two other factors influence the size of a poll’s Democratic lead.  The Democrats do about 2.2 percent worse in online polls than in ones conducted by telephone. On the other hand, polls restricted to “likely” voters show a marginally significant (p < 0.11) boost for the Democrats of 1.3 percent.  That might indicate a slight Democratic advantage in voter mobilization going into the fall, but the effect is still too small, and too variable, to be taken seriously at the moment.

These factors remain constant in the face of changes in Trump’s job approval and the passage of time.  We can thus set them at their values on Election Day and see how the margin in the generic House ballot varies with changes in Trump’s job-approval rating.  This chart presents the likely Democratic lead on the generic-ballot question in polls conducted with live interviewers on Election Day, November 6th. The dotted line represents the effect of adding the small, marginally-significant boost for polls of likely voters:


As of July 20, Trump’s net job approval (approve-disapprove) is averaging about -11 (42-53). My estimates indicate that difference translates into a Democratic margin of 8.8 percent in generic-ballot polls.  Notice that the remaining factors in the model predict a Democratic margin of about six to seven percent even if Trump’s net approval score is zero. That might be a decent estimate of the so-called “blue-wave.”

Models of the relationship between House votes won and House seats won find that, to take back the House, the Democrats will likely need to win by a margin of +7 or better to overcome gerrymandering and partisan geographic self-selection.  For instance, The Economist’s simulation model for the House midterms predicts that the Democrats will win 54.3 percent in November, or a margin of 8.6 percent.  In their model that gap translates into a Democratic seat margin of 224-211, enough to retake control of the House.

History suggests that both the President’s approval rating and support for the President’s party in the House are lower on election day than they are in the spring.

 

Are Some Republicans Leaving Donald Trump?

Recent polling suggests Trump has been losing support among Republican voters since the spring.  Likely Republican voters show less support than other Republicans.

It has become a commonplace among journalists and pundits to observe that Republican voters have remained largely behind President Trump.  Recent polling still shows job-approval ratings for the President among Republicans remaining in the 85 percent range.  But that focus on individual polls obscures a more complex trend, one that does not bode well for President Trump and his Republican Party.

This graph presents the “net approval” score (percent approving minus percent disapproving) for Republican voters in polls that disaggregate their results by partisanship.  Like in the country at large, support for Trump declined during 2017 but has rebounded this year.  (These data end before the decision to separate children and parents at the southern border became a national news event.)  I estimated the trajectory of support using a fourth-order polynomial based on time in office, with the usual array of dummy variables to adjust for polling methods and “house effects.”

The bold line representing the President’s approval rating among likely Republican voters should be especially troubling.  The Republicans most likely to turn out in November average about five points lower on net job approval than do other Republicans.

Even casual examination of the data points displayed here show that Republicans’ opinions about Trump’s performance in office have displayed wide variability since he entered the Oval Office.  However the most recent polling shows a decline in approval since the spring of 2018.

How Popular will the President be in November?

Most presidents are less popular when mid-terms are held than they are in late spring.

In an earlier piece about the “generic” Congressional ballot question, I presented the trends in support for the parties over the course of the summer for a few mid-term elections.  However that question has been asked on a more limited basis than the standard Presidential job-approval question, which Gallup began asking back when FDR served.  As I showed earlier, trends in the job-approval question track inversely with changes in the generic-ballot item. Given the tie between presidential popularity and mid-term outcomes, we might ask how the job-approval question has tracked before mid-term elections.  Given that President Trump’s approval rating stands at a bit under 42 percent today, where might it be come November?

I have compiled Gallup’s job-approval scores for all mid-term elections back to Harry Truman’s second term in 1950.  I have calculated separate averages for first-term and second-term presidents since the additional experience voters have with second-term presidents should limit the effects of most events before the election.

As expected, first-term presidents show a larger change in their job-approval scores than second-termers.  Indeed, excluding the anomalous 1974 election after Nixon resigned, second-term presidents saw their popularity grow on average by about a percentage point.  Nearly all first-term presidents saw their popularity decline as the election grew near, falling an average of 3.8 percent between May and October.

Among first-term presidents, only Jimmy Carter had an approval rating as low as Donald Trump’s at the end of the spring.  Carter saw his rating improve over the course of the summer, but much of that rise came after the Camp David summit with the then-presidents of Egypt and Israel in September, 1978.  Otherwise first-term presidents generally see a decline of about four points on average in their job-approval scores as the summer wears on.  (Leaving out Carter in 1978 raises that figure to five.) On that basis we might expect to see Trump’s job-approval score in the high thirties come Election Day.

One mitigating factor might be that Presidents who start off with ratings under fifty percent show smaller declines than those with a majority of citizens approving of their performance in the spring.  Presidents whose approval score was above fifty percent in May/June watched their ratings fall an average of 4.5 percent by October.  For those Presidents, like Trump, starting with a rating below fifty the average decline was just 1.6 percent.

Will there be a “Singapore Surge?”

Republicans are hoping the Singapore summit will boost the President’s approval ratings, but summit meetings have historically had only small effects. Nor were those effects uniformly positive.

Pundits have speculated that Donald Trump’s meeting with North Korea’s Kim Jong-un might improve Republican chances in the November elections.  “[Trump’s] new willingness to sit down with Kim to work on a peace deal, RNC members believed, would boost his approval rating and make him far less of a drag on congressional Republicans trying to keep control of the House and Senate this November,” wrote S. V. Date in the Huffington Post at the end of last month.  Some of that same optimism was apparent again yesterday. “Ron Kaufman, an RNC member from Massachusetts and once a top adviser to 2012 GOP nominee Mitt Romney, said Trump’s ability to get a meeting with Kim would play well with voters. ‘In real America? Absolutely,’ he said. ‘It will help the president’s numbers, and it will help to some degree in the midterms.'”

The problem with this theory is that summits have had limited effects on presidential approval ratings.  Using the job-approval data from Gallup I compiled the average approval score for roughly the two months prior to a summit and the two months following and calculated the change as shown below.

Most summit meetings have had only marginal effects on the President’s popularity on the order of a few percent up or down.  Nor can we attribute all the changes we see to the summits themselves.  For instance, the fall in Ronald Reagan’s approval ratings after his Washington summit with Mikhail Gorbachev in 1987 resulted largely from the revelations of the Iran-Contra scandal which appeared soon after the summit.  Nor do all summit meetings improve the President’s image. The 1974 meeting between Gerald Ford and Leonid Brezhnev led to the SALT II accords, but they were denounced by Republican opponents like Ronald Reagan and criticized by major newspapers like the New York Times.

A number of summits considered important by historians had little influence on public opinion.  Even an event as tumultuous as Nixon’s trip to China in 1972 increased his approval rating by less than four points.  Kennedy’s supposed failure to stand up to Khrushchev in Vienna cost him a bit over five points. A year before Khrushchev had stormed out of the Paris meeting with Eisenhower over the U-2 crisis.  Eisenhower’s popularity suffered a slightly larger hit.

As I wrote earlier about the effect of the Syrian bombings, opinions about Donald Trump are much too crystallized to react to something like a summit.  And if the intention was to influence the fall election, why didn’t Trump hold out for a meeting in September or October when it might have mattered?  Few voters will be taking the Singapore summit into account when they go to the polls in November.

Update: I added Jimmy Carter’s involvement with the Camp David accords in September, 1978, to the list.  His approval rating rose substantially in the short term, from an average of 40.8 in the two months before the summit to 49.5 in the two months thereafter.  His approval scores were already moving upward after hitting a nadir of 38 the previous July, but they did jump five points between the poll earlier in September and the next sounding in October.  This bump in Carter’s approval persisted through the November, 1978, midterm election.  Perhaps Trump should have waited until the fall to meet with Kim.

This Dog Won’t Wag

Donald Trump’s polling figures showed little change after last year’s attack on Syria.

The 1997 movie Wag the Dog introduced the public to a notion common among pundits and historians, that Presidents like other political leaders might engage in military actions overseas to distract from problems at home.  With a President beset from many sides, pundits have opined whether Friday’s attack on Syrian chemical weapons facilities might have been motivated, at least in part, by the same diversionary motive.

Friday’s action reprises the Tomahawk missile attack conducted by American forces against a Syrian airfield a year ago.  That equally brief sortie had little short-term effect on President Trump’s job-approval ratings and no long-term effects at all.  Here is the trajectory for “net approval,” the difference between the percent of American adults who say they approve of how the President is “handling his job” minus the percent who disapprove.1  President Trump has been “underwater” since his Administration began with more Americans disapproving of his performance than approving.

The most optimistic “wag-the-dog” interpretation of this chart might credit a two or three point positive bump in President Trump’s net approval rating after the attack on the Syrian airfield on April 7th of last year.  Yet a couple of other prominent events might give us pause.  Trump’s approval rating actually improved after Michael Flynn had to resign as National Security Advisor, but it soon fell back down. Last year’s attack on Syria itself took place at a time when Trump’s rating was already recovering.  Perhaps the apparent gain after the attack was just the continuation of that trend.

When partisans are routinely described as “tribal,” we can hardly expect many of them to change their minds about President Trump just because of a single military attack. Republicans endorse his performance in office by margins of 85-10, while Democrats disapprove by an even greater margin of 9-90 unfavorable. For people so solidly entrenched in their partisanship even a missile attack against a sovereign nation can have little sway.

Perhaps, then, we should look at the opinions of self-described “independents.” Maybe their opinions will be more sensitive to current events like a strike on Syria. Sadly those seeking a wag-the-dog effect will once again be disappointed.


Independents’ appraisals of President Trump tracked rather closely to the Gallup figures above (with the exception of the weird spike at the turn of the year).2 Again, whatever small gain the 2017 Syrian attack may have imparted to Trump’s approval ratings among independents quickly dissipated a few weeks later.

 


1Since the beginning of this year, Gallup has reported only weekly job-approval ratings. I appended the 2018 data to the 2017 weekly averages.

2Because Gallup does not report partisan breakdowns, I have averaged together the soundings archived at Pollster that do. This sample includes 313 polls that reported approval ratings for independents. They were conducted by thirteen different organizations, with four each constituting about a sixth of the observations (Politico/Morning Consult, YouGov/Economist, IpsosReuters and SurveyMonkey).

Technical Appendix: Trends in Trump’s Job Approval

I used a relatively simple model to generate the graph shown in the accompanying article.  I ran weighted least-squares regressions against the logarithm of the number of days since the Inauguration and the usual array of dummy variables to account for differences in polling methods and “house effects.”  Here are the results:

 

 

 

 

 

 

 

 

 

 

 

 

The use of the base 10 logarithm shows that Trump’s approval is estimated to have fallen by a bit over five percent between day ten of his term (log(10)=1) and day one hundred (log(100)=2).  I use the percent approval rating in this regression to make the dummy variable coefficients more meaningful.  A regression using the logit of the approval rating shows identical results.

These results show that polls conducted over the Internet or limited to registered voters tend to report a job approval figure about 1.5 percent higher than the consensus.  The “house effects” variables indicate that polls conducted by YouGov/Economist average just under one percentage point less favorable toward Trump than the consensus.  Job approval ratings from polls taken by SurveyMonkey, Politico/Morning Consult, and Rasmussen run from two to five percent higher than the consensus.  Gallup, the most frequent pollster, does not deviate from the consensus.

How Low Can He Go?

In the preceding two articles I analysed the prospects that the Democrats could regain control of the House of Representatives.  The combined effects of gerrymandering and partisan self-selection geographically mean the Democrats face a substantial burden to regain a majority in the House.  Only if the Democrats can win at least 53 percent of the national popular vote for Congress do have they have a decent chance to attain a majority.

The success of the Democrats at the polls in mid-term years depends primarily on two things, whether their party holds the White House, and the President’s job approval rating.  For the Democrats to reach that 53 percent floor needed to retake the House, President Trump’s job approval rating would have to fall to 32 percent or less.

While there have been occasional polls which put Trump’s approval in the low thirties, they have generally been outliers.  I have taken all the polling data available at Huffington Post Pollster since the Inauguration and estimated simple trends that look like this:

The bottom line represents the trend for all adults interviewed in person.  This is the sample used by Gallup, the most prolific pollster in this group.  Registered voters, or citizens interviewed over the Internet, show a slight pro-Trump bias of about one and a half points.  The top line shows the estimate for registered voters interviewed via the Internet.  (Polls of so-called “likely voters” were not significantly different from all polls of registered voters.)

If we take the plunge and extrapolate these trends to the time of next year’s mid-term election (about 650 days in office), Trump’s job approval rating falls only two more percentage points, ranging from 34.6 to 37.9 percent depending on which trend is chosen.  That is still short of the 32 percent threshold I estimated in the preceding two articles.

The results for registered voters should give the Democrats more pause.  The citizens eligible to vote have a more positive view of the President than those who remain unregistered.

 

Can the Democrats Retake the House in 2018?

Now that all the gnashing of teeth has ended after the Republicans managed to hold on to the Georgia Sixth, perhaps we can step back and take a more systematic look at the Democrats’ prospects in 2018. Democrats will likely not make any gains in the Senate since the Republicans have only eight seats at-risk compared to twenty-three Democrats and both independents, Maine’s Angus King and Vermont’s Bernie Sanders.  That leaves the House as the only target.

There are two steps involved in answering this question.  The first is to use our historical experience with House elections to examine how votes are translated into seats.  With that information we can estimate the proportion of the two-party House vote that the Democrats need to win to take back the House in 2018.

As I wrote back in 2012, a combination of geographic clustering by party and good old partisan gerrymandering has created a “Republican bulwark” in the House since the last redistricting after the 2010 Census.  That means that the Democrats will need to win more than a majority of the popular vote for Congress if they intend to win a majority of House seats.

I have refined this simple seats and votes model in two ways.  First, I let the “swing ratio” vary between two historical periods, 1940-1992 and 1994-2016. Empirically the effects of voting “swings” on seat “swings” is significantly smaller in the more recent period.  As Tufte argues in his classic paper on the seats/votes relationship, a decline in the swing ratio indicates an increase in the proportion of “safe” seats.  As fewer and fewer seats have vote shares around fifty percent, there are consequently fewer that can be “flipped” by an equivalent shift in voters’ preferences.

I also use the results for the 2014 and 2016 elections to more sharply estimate the effect since 2010.  If we calculate the popular vote share required for the Democrats to win half the seats in the House, they would need to secure a bit over 53 percent of the (two-party) votes cast.

That brings us to the second question, what are the chances that the Democrats could win 53 percent of the Congressional vote in 2018?  Answering that question deserves an article unto itself.