The New York Observer's Steve Kornacki reminds readers of Bob Kerrey's almost-ran VP candidacy with Bill Clinton as a way of making this point about Biden:

I'm bringing up Kerrey because - and the events of the next 24 to 48 hours may make a mockery of this notion - I have a hunch we're seeing the same thing play out right now with Joe Biden. In the last few days, Biden's stock has risen dramatically. He's leading Drudge's poll (well, technically "a wild card" is - but Biden is tops among humans, by far) and NBC is even reporting that he's "the leading contender, partly due to his working-class roots and foreign policy expertise."

Biden, like Kerrey in '92, makes perfect sense as a running-mate. Obama's biggest challenge is offering reassurance to voters who generally like him and want to vote for the Democrats (or, more precisely, against the Republicans) this year. If Biden is chosen, these voters will be barraged with mentions of his experience, foreign policy expertise and "gravitas." And in perhaps his biggest moment as the nominee, the vice-presidential debate, Biden would almost certainly shine - particularly on foreign policy and national security matters. His working-class Irish-Catholic image wouldn't hurt either. It's true that V.P. candidates can't win over many voters on their own. But the right V.P. can provide the final nudge for voters who are leaning toward a presidential candidate. Biden would be a terrific nudger.

But does he really have much of a relationship with Obama? True, their personal history during this year's primaries wasn't overtly hostile like Kerrey's and Clinton's in '92, but there did seem to be a telling moment during a debate last summer, when Biden announced that Obama had had an H.I.V. test. Rather coldly, Obama jumped in to clarify Biden's comment. His body language was icy. The moment suggested that these two may not be enemies, but they just don't naturally click with each other.

Kornacki is right. We shouldn't discount personal relationships when weighing tickets. The two will go into the meat grinder together and if they don't like each other that could make for a poor fall campaign. It's also true that Biden took his shots at Obama during the primaries -- enough so that if he is chosen, the GOP should get a good ad out of it.

Kornacki believes Obama has the best relationship with Tim Kaine and wants to choose him. I think if Kaine had half of Biden's foreign-policy cred it wouldn't be a contest. But the events of the last couple weeks have raised the importance of having someone with that experience, and so in a battle between head and heart, the head might win.