Alan I. Abramowitz has an insightful post up at Larry J. Sabato’s Crystal Ball. In “It Don’t Mean a Thing if It Ain’t Got That Swing: in Search of the Elusive Swing Voter,” Abramowitz cites a recent AP/Gfk poll alleging that “swing voters — those who are undecided or uncertain about which candidate they will support — make up 27% of the electorate.” However, adds Abramowitz,

But there are good reasons to question whether there are nearly that many voters whose candidate preference is actually changeable. Evidence from a 2008-2009 panel survey conducted by the American National Election Studies shows that the proportion of voters who actually shift their preference during the course of a presidential campaign is much smaller than the proportion who claim to be uncertain about their choice. Moreover, most of the shifts that do take place appear to be explained by voters’ prior party loyalties rather than anything that happens during the campaign.
…Another very common assumption about the American electorate is that independents are very likely to be swing voters. Indeed, the terms independent and swing voter are often used interchangeably. However, evidence from the ANES 2008-2009 panel survey indicates that only a small minority of independents are actually open to persuasion during the presidential campaign.
In January 2008, 32% of respondents in the ANES panel survey described themselves as independents. And these independent voters were, in fact, less certain about their presidential vote choice in June than voters who identified with a party. Only 61% of independent voters were extremely or very sure about their choice compared with 81% of partisan voters. However, despite their lower level of subjective certainty, independent voters were only slightly less stable in their candidate preferences between June and November than party identifiers: 11% of independents switched sides, compared with 7% of partisans. Fully 89% of independents maintained the same candidate preference over this five month period, including 90% of independents who leaned toward a party and 88% of “pure independents” who expressed no party preference whatsoever. Based on these results, the popular image of independents as unstable voters moving back and forth between candidates in response to news stories and campaign events is a major distortion of reality.

And despite the much-trumpeted ‘volatility’ of the current political scene, Abramowitz concludes, “There is every reason to expect that the patterns of stability and change within the American electorate in 2012 will be similar to those found in 2008. In fact, with an incumbent president running for reelection, voter preferences could turn out to be even more stable this year than they were four years ago.” In other words, whether the president is re-elected or not will likely depend more on voter turnout than any notions of a ‘fickle’ electorate.