The clip above explains the rationale, I'd say. The biggest emerging problem with the Obama campaign is Obama's reluctance, lack of talent and lack of will to get into lively, feisty, pissing matches with his opponent. This was brought home in the Saddleback forum. What he needs is a plucky, fun, free-wheeling attack machine, with the necessary gravitas to express adequate contempt for the Bush administration's fatally misguided foreign policy without in any way seeming defensive.

Two further quotes:

"I refuse to sit back like we did in 2000 and 2004. This administration is the worst administration in American foreign policy in modern history maybe ever. ... Every single thing they’ve touched has been a near-disaster."

And this:

"Rudy Giuliani... I mean, think about it! Rudy Giuliani. There's only three things he mentions in a sentence -- a noun, a verb, and 9/11. There's nothing else!"

I have to say his inability to shut up drives me up the wall. But there's also an appealing lack of guile to the man; he wears his flaws like his hair-plugs - out and proud.

And, yes, his foreign policy assuredness cannot hurt. He's a Senator who doesn't just call foreign leaders; they call him. Obama is wise not to under-estimate the understandable worries about his foreign policy inexperience at a time of this much danger for the world.

How the chemistry works, I don't know. Whether Biden can help rally white working class Democrats, as David Brooks suggested, I do not know. Delaware is not exactly Pennsylvania or Ohio. But this was a pick that also demonstrates Obama's ability to bring genuinely independent voices into his inner circle and harness experience greater than his.

Not an inspired choice, in my book. But smart and solid - and adult.