John McCain just surrendered his best case against Barack Obama: that the Democrat does not have the experience to be commander in chief.

By choosing Alaska governor Sarah Palin, who has absolutely no foreign policy or national experience, McCain has taken a huge—and perhaps fatal—gamble.

His bet is that appealing to Hillary Clinton voters and, to a lesser extent, white union voters, is more important than making the now-defunct experience argument.

It’s a risky bet, though, in many ways.

First and foremost, Palin doesn’t appear to be a candidate who is ready, at a minute’s notice, to be President. Given McCain’s age and bouts with melanoma, that could be a big drag.

Second, it’s unclear how she may handle the obstacle course of a national campaign. She could trip clumsily, and end up a disaster like Dan Quayle.

Third, she doesn’t bring a swing state into play. Alaska traditionally goes Republican. It might have been smarter for McCain to go with someone like Tim Pawlenty, who possibly could have turned Minnesota red.

But she solidifies McCain’s support with the social conservatives, as she is an ardent anti-abortion activist and a big NRA supporter.

Most obvious, she and McCain were angling for the Hillary Clinton vote.

Both brought up the anniversary of women’s suffrage. And Palin not only hailed Geraldine Ferraro and Hillary Clinton, she stole Hillary’s line about the 18 million cracks in the glass ceiling. Palin also talked about how she stood up to the “ol’ boys’ network,” a reference that will have wide appeal to women who face routine discrimination in the workplace.

In addition, Palin provides coverage for McCain on the wealth and out-of-touch issue. McCain hailed her and her husband as union members, and Palin echoed that, boasting that her husband is a member of the Steelworkers. After his $5 million mistake and his amnesia on how many homes he owns, McCain could not have very well picked Mitt Romney.

She also may up the comfort level that the Republican ticket has with white voters who may be considering Obama. McCain touted her Norman Rockwell background—her father was an elementary school teacher, her mother a secretary, they taught their kids to play hockey, she coached basketball in turn. All this spells normal, normal, normal for Americans who still find Obama’s background odd.

And note that McCain said she “knows where she comes from.” This was a subtle dig at Obama, and carries the overtone that he’s gotten too big for his britches.

Obama and Biden need to be careful how they respond to Palin. And in a debate, Biden cannot appear condescending or make a stray sexist gaffe. That would feed right into the McCain strategy.

Still, it was a peculiar choice for McCain. It smacks, if not of desperation, at least of bad judgment and recklessness—and those are the very qualities McCain should not be accentuating.