Let's look at my neighbour across the street from my house in Chamblee (15 min outside central Atlanta). He recently had a meeting of minds with my wife over the FUH2 website which posts pictures of people "saluting" Hummers. He carries stickers in his car that read something like "H2: Fuck the environment, I'm rich", along with an assortment of anti-Bush stickers. Yet he is not a Democrat. Like most other white and sensible people I've met in the South he says he's a "Libertarian".I wasn't ready to say this back in March, but I've been thinking about it a lot and now I am: Like Digby says, this "powerful force" is race.
I don't know exactly what it is, but there's some powerful force that keeps Southerners away from the Democratic party. If you're a white male who grew up in the South, and you don't work in a very liberal-minded profession such as education or healthcare, then you're just not going to admit any allegiance with the Democratic party no matter how liberal, environmentalist or even socialist your political views are.
That doesn't mean I think all white conservative Southerners are consciously racist in the sense that they will be hostile to or think badly of individual blacks. The young white Southerners I know treat black colleagues with respect and professionalism. (By the way I heard Barack Obama talk about progress in this area lately although I can't remember where. He said that when he's dealing with a white person one-on-one he doesn't feel that his race is on the white person's mind.)
But when I am in social settings outside of work surrounded by fellow whites I hear views about blacks and black neighbourhoods that don't make empirical sense to me. These assumptions are, I believe, rooted in tradition and history. Talk about how un-safe certain neighbourhoods are, for instance. I get a sense there's no point in asking if they've ever visited these neighbourhoods, or know somebody first-hand who has. That's irrelevant. There's just a clear sense that "they" are very different from "us".