An interesting nugget from the Times about the Dems' win in that Mississippi special election last night:
In the end, tying the white Democrat to the black presidential candidate may have helped Mr. Childers more than it hurt him, as campaign aides reported heavy black turnout, heavier than in a vote three weeks ago when he came within 400 votes of winning.
“I like what Childers was saying: he was more truthful and down to earth,” said Mary Shelton, an African-American who had just voted for him at the Yalobusha County courthouse here.
And Mr. Childers’s association with the party that might nominate Mr. Obama didn’t hurt either. “We need a change, we really do,” Ms. Shelton said.
Mr. Childers won Yalobusha, having lost it in the April vote.
And even in this district, it is not difficult to find conservative voters dissatisfied with the administration in Washington. “There’s a lot of people that are mad at Bush,” said Jim Jennings, a retired businessman, sitting at a table with Republican voters at a barbecue restaurant in DeSoto County.
It sounds like Obama helps with turnout more than he hurts with swing voters in a conservative district like this one.
I don't see Obama carrying many Southern states (though making McCain spend time and money defending Georgia, North Carolina, and Virginia would be a big plus in itself.) But you can imagine him helping Democrats pick up some Southern House seats thanks to this dynamic.