Appropos of Phil’s post on this Washington Post piece, as well as this Newsweek piece cited by Brendan Nyhan, here are three studies — two published, one informal — that speak to this question.
First, see Zoltan Hajnal’s book on white attitudes toward black mayors. He concludes:
bq. [U]nder most black mayors there is real, positive change in the white vote and in the racial attitudes of white residents. This change occurs because black incumbency provides concrete information that disproves the fears and expectations of many white residents. These findings not only highlight the importance of black representation; they also demonstrate the critical role that information can play in racial politics and point to the ability of at least some whites to change their minds about blacks and black leadership.
Second, as I’ve noted before, Ben Highton looked at a large sample of House races and found that white voters were no more or less likely to vote for black candidates. He writes:
bq. To conclude, although African American “victories [in majority-white areas] attract attention precisely because of their exceptional nature” (Lublin, 1995, p. 112), one should not automatically assume that their rarity results from discrimination by white voters. Given the evidence presented here, the barrier presented by white voters in general elections does not appear especially daunting, especially in relation to the barrier it is often perceived to be.
His paper is here.
Finally, Seth Masket recently undertook a quick study of black candidates in Senate and gubernatorial races in 2002-2006. As he notes, the important caveat is that there have been few such candidates — 10 altogether, and 2 of those (Obama and Alan Keyes) actually ran against each other — and so that data are thin. Nevertheless, Seth also finds that race did not have a significant impact on the candidate’s vote share.
He then did a second analysis, focusing on black Democratic candidates. He computed the “expected” vote share of these candidates, based on several factors, such as the state’s partisan leaning and incumbency status. He then compared these candidates’ expected vote to their actual vote. He found, at best, a small discrepancy:
bq. In each of the four contests, the African American Democrat ran behind the expected vote, although not by much…In only one of these cases (Ford) did the African American candidate lose where he “should” have won.
bq. Incidentally, the story is much less consistent for the black Republican candidates. In two cases, they ran ahead of the expected vote, and in two they ran behind. None got within 10 points of winning, though.
Of course, there are ways in which this year’s presidential race may not be comparable to Senate, House, gubernatorial, and mayoral races. Perhaps presidential races are just different. Perhaps Obama is different. But these studies are worth taking into account going forward.