McCain's surprise choice of Sarah Palin is a gamble that picking a solid conservative and non-Washington insider with a bit of a reformist record will outweigh the clear downside: That choosing someone with only two years in high office as back-up president undermines attacks on Obama's alleged lack of commander-in-chief readiness.

By any reasonable measure, Palin's resume should render it all but impossible to argue that Obama is too inexperienced for the gig of leader of the free world.

Palin has been in higher office as Governor of Alaska for exactly half the time Obama has been in the Senate. Before that, she served only two full terms in the City Council, from 1992 to 1996, before running for mayor of Wasilla.

To put this in perspective, Wasilla had a population of only 7,738 people as of 2004. By contrast, as TPM's Eric Kleefeld calculates, Obama's State Senate district had roughly 210,000 people -- about 27 times the number Palin repped in lower office.

Nor has Palin been tested in the grueling arena of national politics. She'll be forced to face off in a debate against Joe Biden, who's been in the Senate nearly 20 times as long as Palin has held higher office; Biden is well known to diplomats in world capitals.

On the plus side for McCain, Palin brings some much-needed "estrogen to the ticket," as one Obama hand remarked to us.

She's the sweetheart of Alaska: Attractive, young (44), a hockey mom, feminine and strong (beautiful and a member of the NRA!). Palin could appeal to a generation of women who respect strength and independence in women, but don't necessarily identify with the feminist movement. She has also managed to achieve higher office while coming across as someone who puts family before career.

There's a powerful maternal narrative, too: In April, she elected not to have an abortion when she discovered that her baby had Down's Syndrome. And for good measure, she also has a son in the army named "Track" who's set to deploy to Iraq.

The selection of Palin, of course, is also a bid for the disaffected Hillary vote, though it's unclear how disaffected that vote is now that both Clintons have offered full-throated endorsements of Obama.

Palin is also a sign that there was never much to the speculation that McCain would choose someone with indy cred. She's a solid conservative who will thrill the right-wing base.

Palin is strongly anti-abortion, and only makes an exception on abortion for the life of the woman -- excluding even rape and incest. One area where she has deviated somewhat from the conservative line is gay rights, having vetoed a bill to ban domestic-partner benefits for gay public employees.

Palin also supports the teaching of creationism in public schools, under the name of "intelligent design."

Palin also has some reformist cred that could resonate with McCain's history. In 2006 she was elected governor after running on a "clean government" platform and has shaken up Alaska by targeting corruption in local government. But she's recently been dogged by a scandal over her firing of her public safety commissioner, allegedly because the commissioner refused to fire her former brother-in-law, a state trooper, who has been involved in a nasty and long-running dispute with the Palins.