One might use different words to describe what BC's talking about, hit the point harder or softer. But I think the essential observation is an acute one. Let's be honest. If you live in the South, and you've got issues with black people, you're already voting Republican. In states of the old industrial heartland, where racial tension crosscuts ties of unionism and economic populism, that's much less clear.
I was canvassing for Obama in OH from Saturday through Election Day, but I still expected Clinton to win. My reasons were in part anecdotal: Despite working with a solid Obama ground organization, I encountered much starker resistance from older, middle- and working class whites than I had in other places I'd canvassed, namely Maryland and Iowa. But this anecdotal evidence only added to the much more extensive sense of the Ohio electorate I got as the field director on a House race there in 2006.
The impression I came away with then, and had reinforced last week, was that in today's America race is actually more of a factor in the Democratic politics of "border states" like Ohio, Tennessee and Indiana than it is in the "Deep South." In the latter region, racism has been thoroughly integrated into Republican politics while the kind of counter-forces that would keep racially conservative whites aligned with Democrats -- primarily unions and economic populism -- are virtually nonexistent.
In the "border states," though, you have a collision between old patterns of racist sentiments bleeding up from the South and traditions of populism and white working class unionism bleeding down from the Rustbelt North. Ultimately, I think this means that while you may find more out-and-out racists in Alabama or Texas, you're more likely to encounter latent racist sentiment among a broad segment of Democrats somewhere like Ohio or Tennessee.
If I'm right, this could be at least a partial explanation for why Obama performed better in southern, red Texas than in midwestern, purple Ohio. It could also explain the odd pattern we've repeatedly seen of Obama performing very well in both the states with the highest African American populations and the lowest, but not as well in those in the middle where ethnicities are more mixed.
I think this is one facet of the race/gender issues in this campaign that the media actually hasn't beaten to death -- in fact, they've barely addressed it. We've heard a lot about Hillary's appeal to women giving her an advantage with them, a lot about how well Obama does among blacks, and even some mutterings about whether Obama's youthful and yuppie white support has to do with those groups wanting a "token black friend"; but almost no one has stopped to ask whether Clinton's consistent lead amongst white working class Democrats might have something to do with race. I'm almost certain it played a role in her margins of victory in states like Ohio, Tennessee, and Oklahoma.
I'm also not sure what this means if true, either for the rest of the primary or the general. I guess the question for the primary is whether latent racism exists amongst Pennsylvania's white Democrats to the same degree that it does in Ohio. And for the general, if Obama wins, I'd say the question is whether racial suspicions in swing states like Ohio are so strong that a significant portion of white working class Democrat-leaners would ignore their economic concerns to vote against him, or whether it's a more subtle thing that just nudged them into a preference for Clinton in the primary, but will be trounced by devotion to economic progress in November.