Does Obama Have McCain By the Balls?

Nate Silver breaks down the swing votes in the upcoming Senate. Along with Nate's usual fascinating analysis, was this nugget that captured my imagination:

McCain (AZ). Hard to know where his headspace will be for a variety of reasons, particularly as he's legislated all over the spectrum (from authentically moderate to strongly conservative) in different Congresses. Obama may have sent him something of an olive branch by appointing Janet Napolitano, his potential rival in 2010, to head of Homeland Security.

Perhaps nominating Napolitano was an olive branch for McCain, but she could just as easily become a guided missile. If John McCain spends the next twelve to fifteen months being difficult, then maybe, all of a sudden, Napolitano decides she needs to spend more time with her family, er, I mean, kicking McCain's ass for his Senate seat in 2010.

If, however, John McCain turns up the mavericky shtick and throws down on a few cloture votes, maybe Napolitano decides that she likes running the Department of Homeland Security just fine.