When Democrats have won, the Democratic vs. Republican vote has been close among whites -- 47-52 percent in 1976, 39-40 percent in 1992 ,and 43-46 percent in 1996.
There are differences in commitment.
Among blacks who support Obama, 93 percent say they'll "definitely" vote for him; fewer whites who favor him, 67 percent, are "definite" about it.
And among all blacks, 87 percent are enthusiastic about Obama's candidacy, including 73 percent "very" enthusiastic. Those fall among whites to 53 percent enthusiastic, 21 percent very much so.
Similarly, 90 percent of blacks have a favorable opinion of Obama overall, 77 percent "strongly" favorable. Those are 58 percent and 32 percent, respectively, among whites.
In another measure, 87 percent of registered voters describe themselves as comfortable with the idea of Obama as the first African-American president; 11 percent are uncomfortable with it, including 6 percent "entirely" so.
For comparison, that's much less than the level of discomfort -- 45 percent -- with McCain taking office at age 72.
Blacks nearly unanimously pick Obama over McCain as the candidate who best understands their problems and best represents their personal values, as well as on other personal qualities and political issues.
But Obama is competitive among whites on some fundamental personal qualities as well.
Forty-six percent of whites say Obama better represents their personal values, about as many as the 48 percent who pick McCain. And whites divide evenly, 43-42 percent, on whether Obama or McCain "better understands the problems of people like you."
There are sensitivities about race that may yet play out in the campaign.
Roughly equal numbers of Americans -- about a quarter in both cases -- say Obama and McCain alike are trying to make Obama's racial background more of an issue than it should be.
There are both partisan and racial aspects to these views.
Democrats are much more apt than Republicans to say McCain has been trying to make Obama's race more of an issue than it should be (38 percent vs. 10 percent), and this view peaks among blacks, with 51 percent saying McCain's trying to make too much of it.
Twenty-three percent of blacks, meanwhile, say Obama himself is trying to make his racial background less of an issue than it should be. But 69 percent say he's handling it about right -- and 65 percent of whites concur.
METHODOLOGY: This ABC News/Washington Post poll was conducted by telephone Aug. 19-22, 2008, among a random national sample of 1,108 adults, including an oversample of African Americans (weighted to their correct share of the national population), for a total of 201 black respondents. Results among registered voters have a 3-point error margin. Sampling, data collection and tabulation by TNS of Horsham, PA.