One more quick one on Chuck Hagel. Kevin Drum argues that GOP opposition to Hagel is personal, based on his lack of loyalty to the party: "It's crazy and off the rails, but it's also personal."
I think it's reasonable to suspect that Hagel's turncoat actions made him a target, and I think Drum is right to say that it's been underappreciated (including by me, in my item earlier today). But if it's really exactly that -- what an article Drum quotes from lists as tacit support for Obama over McCain in 2008, and support for Bob Kerrrey over Deb Fischer in last year's Nebraska Senate contest -- then I'm not sure that I'd really say it's personal.
Parties have very strong incentives to enforce partisan loyalty on their elected officials. That's especially true, and difficult, in the US system, with it's decentralized and relatively open nomination system. Basically, it's really hard to punish incumbents when renomination has an enormous incumbency advantage.
Now, given that we're talking about McCain, it's certainly possible that it's purely personal...McCain certainly appears to be acting on personal grudges half the time, regardless of what other incentives are going on. And it's also possible that there are other things in the "personal' column having to do with Republican Senators relationship with Hagel when they were in the Senate together.
But as far as institutional incentives: when you get a chance to punish a disloyal party politician, it makes sense to do so. That's not personal; it's (party) business.