In 2008, the president won 95 percent of the black vote, as opposed to about 90 percent for Gore and Kerry. What’s more, African Americans turned out at a much higher rate than they had in previous cycles, clocking in at 13 percent of the total electorate rather than the 11 percent of turnout they had generated in earlier years. This means that Obama won more than just the core Democratic vote – he also picked up a solid chunk of the black Republicans and typical non-voters supported him. All told, his extra haul with the African American vote in 2008 accounted for about 40 percent of his total victory margin over John McCain.

And this is where his flip flop on gay marriage might hurt. The roughly 10 percent of the African American population that does not count itself a Democratic constituency might swing back to the GOP this cycle, in part because of gay marriage (though, there might be other reasons, too: the economy, namely). That would cost Obama votes. Ditto if usually non-voting African Americans decide to stay home; Obama convinced many of them to head to the polls in 2008, but he might have trouble doing that again…

So, I doubt that the White House expects to lose many votes here. But there is a broader issue with Obama and the African American vote: The 2010 midterm found the Republicans moving back up to their long-run average of about 10 percent of the African American vote, and it also showed turnout ticking back down to its historical levels. Additionally, the Gallup weekly poll usually finds Obama closer to the 90 percent support level among African Americans than the 95 percent he pulled in 2008.