PRINCETON, NJ -- Eighty-six percent of voters who say they voted for Barack Obama in 2008 are backing Obama again this year, a smaller proportion than the 92% of 2008 John McCain voters who are supporting 2012 Republican candidate Mitt Romney. Nine percent of 2008 Obama voters have switched to supporting Romney this year, while 5% of McCain voters have switched to Obama.

The results are based on July 23-29 Gallup Daily tracking with more than 2,000 registered voters who reported voting in the 2008 election. Of these, 48% said they voted for Obama and 42% McCain, with the remaining 10% saying they voted for another candidate or not disclosing their vote choice. However, the six-percentage-point advantage in reported voting for Obama is similar to the actual seven-point edge he had over McCain in the final 2008 returns, 53% to 46%.

Obama and Romney have been tightly matched so far this year, with the two generally tied or one having a slim one- or two-point advantage among registered voters in Gallup Daily tracking.

Thus, it follows that fewer voters are supporting Obama this year than in 2008. But the race remains close because Obama's margin in 2008 was large enough that he could still be tied or in the lead this year if his support is a few percentage points lower.

The data do underscore the high degree of party loyalty in voting across the last two elections. All told, 79% of registered voters are supporting the same party's candidate in 2012 as in 2008. That figure understates the true degree of party loyalty because the loyalty of the substantial minority of voters who did not report their 2008 vote choice cannot be computed. Among those who say they voted for either Obama or McCain in 2008, 89% are supporting the same party's candidate in 2012, leaving 11% who are either supporting the other party's candidate (7%) or are undecided (4%).

Nonwhites other than blacks, a group composed largely of Hispanics and Asians, are among the subgroups of 2008 Obama or McCain voters most likely to switch presidential preferences or be undecided this year. Twenty-one percent of this group of voters have a different preference now than in 2008, about double the national average of 11%.

Other groups showing an above-average shift in vote choice between 2008 and 2012 are political independents (18%), political moderates (16%), Eastern residents (15%), those with a high school education or less (15%), and unmarried men (15%).

Implications

The vast majority of U.S. voters are remaining consistent in their voting preferences between 2008 and 2012, be it for Barack Obama or the Republican presidential candidate. But loyalty to Obama is slightly less than loyalty to the Republican candidates, resulting in a more competitive race at this point than in the final 2008 results.

The 11% of 2008 Obama or McCain voters who have switched to supporting the other party's candidate or are undecided at this point is not a relatively large group. But it is a group that could potentially be persuaded between now and Election Day, and thus could be crucial in deciding the outcome.

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