Presidential primaries often feature ups and downs, and comeback stories are not infrequent. But the phenomenon is unusually pronounced this season. What's the reason? There are two basic factors at work: The field's lack of an "acceptable" nominee, and the way voters react to new candidates.
First we will consider the way Republican primary voters tend to greet candidates with whom they are not very familiar. Voters seem to make positive assumptions about their candidates. Simply by virtue of a candidate's presence on the stage, voters assume that the candidate--barring evidence to the contrary--is a "legitimate" one. A proper Republican candidate is both conservative and electable, and voters presume that anyone on the stage possesses both qualities.
In fact, it seems that voters are very optimistic in their assumptions. While virtually all Republican officeholders have taken a few positions that aren't conservative, voters have an "innocent until proven guilty" approach: The candidate has never strayed from conservatism. It's up to the media and the other candidates to prove otherwise. Similarly, a candidate is presumed electable.
The reality is far different. Trump was neither conservative nor electable, Bachmann was unelectable, Perry had holes in his conservatism and proved more incapable in debates than anyone could have imagined, Cain was so unelectable that he had to quit, and Gingrich is vulnerable on both attributes. Once each of these candidates got high enough in the polls, the media and other candidates illuminated the voters.
By contrast, Mitt Romney's numbers have been remarkably steady over the course of the primary. That's because voters already got to know him during the 2008 primary. If there's something you don't like about Romney, you probably knew about it before the 2012 primary began--you didn't hear about it for the first time this year in a negative ad.
The second factor has to do with the current crop of candidates. As Elephant Watcher observed at the beginning of the primary season, there is a void in the field: No single candidate is capable of both exciting the Tea Party wing and pleasing the establishment wing of the Republican Party. Chris Christie was capable of doing both, but he declined to run. Mitch Daniels and Tim Pawlenty were capable of at least being acceptable to both wings of the Party, but Daniels declined to run and Pawlenty quit prematurely.
The result is that there is no "acceptable" candidate in the field. This means each time a frontrunner came under attack, the voters could learn something that made the candidate unacceptable, and the candidate's poll numbers took a nosedive. If there was a broadly acceptable candidate, he would have survived the vetting process and remained in the lead. This season, that couldn't occur.
Once a candidate wins enough state contests and clinches the nomination, Republicans are likely to put aside their doubts and rally around the candidate. But that won't happen while it's still time for the voters to shop.
