Look, if you saw the numbers that I saw last evening, Southern Democrats (as well as Appalachia) will be often running against Obama at every chance they get. At least the smart ones will.
A remarkably poor argument. The Democrats are not dependent on the southern block in the party (at least not those in any danger of losing) at all in order to pass legislation in the House. In the Senate, Rockefeller, Byrd, Pryor and Lincoln are popular enough to easily win reelection regardless of what they do (within reason, of course) while Landrieu is also not necessary. They certainly won't be voting against their party with any regularity, much as Snowe and Collins spent very little time voting against their party (at least on the actual agenda, when it was needed) yet easily won reelection in 2006 and 2008. More importantly, those regions are still not anti-Democratic regions, and Obama really has nowhere to go but up in places which aren't sure whether he plans to put white people in camps and declare Sharia law.
^^^^^^^
There just aren't that many white Southern Dems anymore and the national Democratic majorities aren't that narrow anymore. White Southerners and their interests now hold less sway in national politics than any time since the 1920s.