Undecideds split evenly using data from five elections
Post-Election Reported Vote for Pre-Election Undecideds and Third-Party Voters
I extended the analysis of undecided voters described in the preceding post using the American National Election Studies for all Presidential elections starting in 1980 where an incumbent was running for re-election. There is no evidence that undecideds broke disproportionately for the challenger in any of these elections. Reagan did best among the challengers, picking up 43% of the undecided vote compared to Carter’s 34% in 1980. However this advantage probably had as much to do with Reagan himself as with his challenger status that year. Four years later when Reagan was the incumbent he outdrew Mondale among undecideds 47-41. In the three other elections undecideds were just as likely to give their votes to the incumbent as to the challenger.