When Bush no longer works as a foil
Nate Silver hits on the fundamental quandry facing the blue dogs, especially those who came to power during the Bush years:
The fact is, Mr. Blue Dog, there's a good chance that the reason you're in power is because George W. Bush was in power. When Bush was in power, you didn't have to advance your party's own agenda -- you just had to block some of the more unpopular elements of his.
But you don't have that advantage anymore. You're going to have to endure at least two more elections with Obama as your President -- and since the Republican candidates in 2012 are Dopey, Sleazy and Romney, probably four. You're going to start having to find at least a few things to vote for.
And if health care isn't one of them, it's hard to see what else is, at least in your sort of district.