Some quick thoughts about veep nominee Joe Biden, in the midst of a dash to the airport and a flight to the Democratic convention in Denver:

I've already provided the gist of the case for Biden, in the piece that appeared here on Tuesday. But there's more on the potential upside. For starters, his Catholic blue-collar roots could help Obama in the Rustbelt working-class communities; Obama obviously needs to nail down Pennsylvania (Biden, a familiar face in Pennsylvania media markets, hails from Scranton) and win pivotal Ohio, where Biden, a visceral campaigner, might be a help in connecting with economically anxious voters.

His three-decade voting record is basically middle of the road, at least for a Democrat, which means the McCain camp will have trouble painting the opposition ticket as too liberal. And the liberal base/blogosphere, while not necessarily enamored of Biden (who did, after all, vote for the disastrous Iraq war resolution), is nevertheless impressed with his strong debating skills (on flagrant display during the '08 primary season) and his willingness to bloody the GOP. And while Hillary Clinton's bitter-enders will be displeased that their candidate didn't get the veep nod, women voters will no doubt learn that Biden's legislative achievements include sponsorship of the 1994 Violence Against Women Act (hailed at the time by the National Organization for Women as "the greatest breakthrough in civil rights for women in nearly two decades").

On foreign policy, Biden's expertise is respected even by many Republicans, and John McCain now faces the challenge of finding a running mate who can effectively duel with Biden on those issues in the October veep debate. (My guess is that Minnesota Gov. Tim Pawlenty's stock just plummeted.) And there's another policy area where Biden might be of assistance: the future of the U.S. Supreme Court. As a former Senate Judiciary Committee chairman, Biden can make the argument to wayward women voters that Roe v. Wade is hanging by a thread and that the next president will be making several appointments that could swing the high court either way.

And on the governing front (assuming, for the moment, that Obama wins), Biden would be well positioned to act as Obama's ambassador to the Senate, particularly when a few more votes are needed.

The downside of picking Biden?  He has said a zillion things, and in 35 years he has voted on a zillion pieces of legislation, and all those zillions are potential grist for the GOP. We're seeing that happen already this morning; the McCain camp has cranked out a new ad that refers indirectly to a remark that Biden made about Obama in August 2007: "I think he can be ready, but right now I don't believe he is. The presidency is not something that lends itself to on-the-job training."

Biden will obviously say now that Obama has gotten plenty of seasoning during the past 12 months. Maybe that will work, maybe not. The larger McCain strategy will be to spin the Biden nomination as vivid proof that a grown-up was needed to buttress the untested kid who tops the ticket. (The problem with the McCain spin, however, is that the GOP did exactly the same thing in 2000, tapping Dick Cheney to buttress George W. Bush.)

But who knows how much of this will matter, given the fact that running mates rarely make a difference on election day. The bottom line, however, is that with Biden now in the game, it will not be dull.

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And here's something for the political trivia geeks:

Despite all the summer speculation that Obama might pick a governor as his running mate - with Tim Kaine and Kathleen Sebelius topping that list - it's worth taking a little quiz. Take a guess how many governors have been tapped as running mates by Democratic presidential nominees during the past half-century.

Zero.

Now take a guess how many times since 1952 Democratic presidential nominees have NOT chosen a U.S. senator to fill out the ticket.

Once.

That was in 1984, when Walter Mondale picked congresswoman Geraldine Ferraro.  All other running mates were senators: John Sparkman in 1952, Estes Kefauver* in 1956, Lyndon Johnson in 1960, Hubert Humphrey in 1964, Ed Muskie in 1968, Tom Eagleton* in 1972, Mondale in 1976, Lloyd Bentsen in 1988, Al Gore in 1992, Joe Lieberman in 2000, and John Edwards in 2004. (Eagleton was dumped after being chosen, in the wake of revelations about past mental illness. Kefauver was actually chosen by an open convention, but presidential nominee Adlai Stevenson said OK. And I'm not counting 1980 or 1996, the Democratic incumbent elections.)

So Biden is actually part of a grand Senate tradition - which may well be another reason why there is always so much roiling ambition in the Cave of Winds.