So if the electorate stays on trend, the minority share of voters in 2012 should not only match but exceed its share in 2008, significantly helping Obama’s re-election bid. But will these voters show up in their expected numbers? That is where Obama could run into trouble. The real guarantor that they will is voter enthusiasm. Lacking that, the expected increase in minority vote share might well not appear. After all, in the 2010 election, when enthusiasm was not high, minority vote share dropped to 23 percent, a poor performance even for an off-year election.

And enthusiasm does appear to be a question at this point. As documented in a recent Pew poll, as economic pessimism has mounted, approval of Obama has dropped. And that has definitely affected minority enthusiasm for Obama. Approval of Obama among blacks has declined by 10 points from recent highs and judging from Gallup data (Pew does not break out Hispanics) there has been a decline of similar magnitude among Latinos. Indeed, these data show Obama’s approval rating among Hispanics dipping below 50 percent, a very poor performance among a group who must turn out solidly for minority vote share to increase.

And what about Obama’s 80 percent support from minority voters? Can he plausibly hope to maintain that? That’s a tough target. In the two other presidential elections of the last decade, Democratic Presidential support among minorities was lower: 71 percent in 2004 and 75 percent in 2000. My estimates suggest that he could live with the mid-range of recent results—75 percent—perhaps driven by some falloff in black support from its astounding 95 level in 2008. But lower than that and I believe his candidacy is seriously weakened.