Obama's black support appears to come most fervently from those like his half-brother (click on the graphic to see it more clearly):
As income, education, and unemployment levels rise, so do opinions of Obama among American blacks. If he were to take the Presidency, how would he be effected by the relative ambiguity with which lower class urban blacks feel for him? Will it further inflame the specter of he inevitably turning out to be no different from the Beethoven-listening, Shakespeare-reading Stanford graduate with whom he shares a father?
Taking a closer look at the graphic excerpted from a WSJ article earlier in the week, a couple of things emerge. The polling was done in October, before accusations of playing race and gender cards began being made by campaign surrogates, and when Obama was still the raceless candidate in media portrayals. So it may be that the raceless Obama--with weird facial features, a weird name, and the love of rich whites--didn't appear attractive to the real community. Now that he is, in clobbering Hillary by picking up 83% of the black vote in Nevada, inevitably being cast as the black candidate, those poll results might be too dated to rely on.
Yet this ambiguity among blacks is probably crucial for his candidacy to be viable at the national level. If he becomes the champion of black America, he doesn't stand much of a chance. He'll come up against the sobbering fact that blacks comprise just one-tenth of the voting electorate, and can guarantee him only the 3 electoral votes from DC that are already slated for whoever has a (D) by the name. Moderate white Americans (keeping in mind that 80% of votes will be cast by whites) will shy away from a campaign perceived to be fueled by racial politics. Hispanics, who voted for Hillary in Nevada at a rate of more than 2-to-1, will recoil as well.
Obama is aware of this. He hasn't been running his campaign in a way that suggests he is insecure in his level of black authenticity. To the contrary, he's treated it as a non-issue by, well, not alluding to it, let alone dwelling on the subject. It's certainly conceivable that even if this frenetic identity crisis still characterizes many of his thoughts, in order to become President and maintain a high approval rating while serving, he could squelch it entirely.
You have to wonder, too, if he hasn't realized since winning a Senate seat that his identity crisis is an enormous hinderance for his aspirations from this point forward. As a sharp leftist with a great voice* and a few exotic elements (name and ancestry), his most viable appeal is to affluent Democrats, black and white--the kind of people who gave him Iowa. He will never be able to outpander a Jesse Jackson or an Al Sharpton (and he might've been better off if the latter had made another run, ginning up the black community that would eventually fall in behind Obama once Sharpton bowed out, while redirecting the speculation on race politics via Obama to the overt conversation about race via Sharpton).
As Steve Sailer has said several times, though, it would be illuminating for him to speak to it directly.
* As I see it: Edwards' southern 'hick' sound combined with his leftism and failed '04 bid create a tired Jimmy Carter feel, Hillary screeches in a way that few married men can stand, Giuliani has a sissy lisp, Romney feels like a debate captain who is trying to pour out all the stats and facts rolling around in his head as quickly as possible, McCain sounds snide and stand-offish, and Ron Paul has a squeaky Elmer Fudd element in his voice. Obama, by contrast, is deep, powerful, and measured. Huckabee has the command of a successful Protestant pastor giving a sermon, and the only one who surpasses Obama.