President Obama’s loses his lead in national likely-voter polls after the Denver debate

Following the same procedures discussed in other postings here, I have regressed the size of the Obama lead in polls of likely voters taken after July 4th against the number of days remaining in the election and a dummy variable for polls taken after the October 4th debate.  The results above show that the President was following nearly the same trajectory in the polls prior to the debate as he did in 2008.  The estimated polling margin for Election Day calculated using pre-debate polls is an Obama victory of 6.0%.  The post-debate shift of -5.4 in Mr. Romney’s favor puts the Election Day margin of victory at just 0.6% in favor of President Obama.

OLS, 2012 Likely Voter Polls after July 4th (N=53)
Dependent variable: Obama lead over Romney

               coefficient   std. error   t-ratio   p-value 
  const         6.01935      0.933589      6.448    4.39e-08 ***
  DaysBefore   −0.0534490    0.0139228    −3.839    0.0003   ***
  PostDebate   −5.38442      1.00644      −5.350    2.20e-06 ***

Mean dependent var   2.150943   S.D. dependent var   2.884949
Sum squared resid    267.6344   S.E. of regression   2.313588
R-squared            0.381610   Adjusted R-squared   0.356875

The coefficient on DaysBefore indicates that the President would pick up an average of 0.05% as each day of the campaign passes.  That rate of gain is a bit slower than in 2008 when it reached 0.06%.  In 2012, President Obama was on track to gain a full percentage point in the polls every twenty days.  If he continues on that path, he would be marginally ahead of Mr. Romney by 0.6% come Election Day.