I was going to post about Evan Bayh's bizarre vote with the Republicans against the Obama budget (as well as his even weirder vote in favor of the fiscally irresponsible Republican budget filled with tax cuts for extremely wealthy people like... Evan Bayh), but then Rachel Maddow covered it and this is better than what I would have written:
I disagree with Ana Marie Cox's assertion that Bayh put the will of his constituency above the needs of his party. Obviously he went against both the needs of the constituency and the direction of his party, but it's not like he was going to face a tough reelection here in Indiana. He's a well-loved Hoosier, Republicans aren't going to spend much to fight him, and I really, really doubt he'll be primaried from the left in 2010 in Indiana (and his votes on the budgets wouldn't help much if he were).
No, I think it has something to do with this chart from Ezra Klein:
On the left is his and Ben Nelson's (D-NE) rank as the most conservative Senate Democrats (Bayh is in blue). From 2001-2006 Nelson was the most conservative Democrat in Senate, but was only beaten out from 2007-2008 by Evan Bayh. That's a noticeable rightward shift for someone who doesn't have to worry about reelection.
(2005-2006 is also interesting, but his move to the center of the party can probably be explained by his playing with the idea of running for president in 2008.)
He's moving further and further to the right now that he knows he doesn't have to please the party. It could be because he's worried about his own taxes, or it could be because there's a bunch of attention that comes with being the liaison between Democrats and Republicans. He's been talking about forming a group of moderate Democrats for months, and I doubt the fact that he would be the leader of said group is something that doesn't play into his calculus.
Or it could be the insane amount of lobbyist money and campaign contributions he got from the financial sector. But why they'd want him to oppose the stimulus package (which the Republican budget would have eliminated) is beyond me. It's only a fraction of the money they've been getting and a financial sector functions better in a healthy economy.
Then again, these folks aren't known for their ability to think long-term.