John McCain completely upended the presidential race by tapping Sarah Palin, an unknown and unremarkable governor of a small, remote red state, to be his running mate. McCain won the GOP primary largely by positioning himself as a man among boys, and he’s been depicting the general election as choice between the old soldier you know and a new, untested lightweight. Yet now McCain’s ticket carries the weakest link, according to the instant judgment of the political class. Noting Palin’s youth, inexperience and "ethical shadow," the AP dryly recited Palin’s governing experience: "A governor for just 20 months, she was two-term mayor of Wasilla, Alaska, a town of 6,500 where the biggest issue is controlling growth and the biggest civic worry is whether there will be enough snow for the Iditarod dog-mushing race." Journalist Josh Marshall also concludes that Palin shreds McCain’s greatest hope for victory. "With her choice, McCain, with one stroke, undercuts the best argument of his campaign: Obama’s purported lack of experience for the job."

So did McCain really just sabotage his own presidential run? Not even close. This is probably the best move he’s made during a largely lackluster campaign. Yes, Palin remains an odd choice — she aspires to Barack Obama’s youthful appeal, but without the substance or credentials, and she aims for Hillary Clinton’s tenacity, but without a clear policy agenda. (That’s why some conservatives are dispirited.) Yet Palin could deliver major political, message and substantive dividends — for McCain and perhaps for the country.

Politically, she may lure independent women and former Hillary supporters. Surely GOP polling reflects that prospect, given McCain’s recent ads courting those cohorts. For McCain’s message, putting a new, young female politician on the ticket signals far more change — and validates the maverick promises — than the prospect of two senior citizen senators who pledge to "change Washington."

Substantively, which is most important, McCain is using his campaign as a vessel to break another glass ceiling in America’s overwhelmingly (white) male-dominated power structure. It may be good politics for him, but it’s also good for a Republican Party that grooms few women, and virtually no minorities, for leadership positions in government. (President Bush is a welcome and rare exception, as I’ve written before.) It’s good for the country — remarkable, inspiring and also long overdue — that both presidential tickets promise to break a barrier fortified by America’s long history of discrimination. The Democrats clearly deserve more credit for this progress, given decades of work backing civil rights and educational opportunity, along with the more recent activism of Democratic voters willing to "risk" their votes on a Jackson or Ferraro, and an Obama or Clinton. It would be a bitter irony, for many Americans, if the political climate developed by Democrats and Sen. Clinton redounded to benefit a Republican woman who did not place herself in the race for national office.

Clinton, however, struck a supportive note in her first official response to Palin’s "historic nomination." After congratulating the Alaska Governor and Sen. McCain, Clinton noted that "while their policies would take America in the wrong direction, Governor Palin will add an important new voice to the debate." It is a voice, of course, that shouts down much of Clinton’s life-long work — and speaks in stubborn opposition to the economic and foreign policy changes favored by the public. Yet it is also another step towards delivering on the promise of American democracy, the selection of a government from all the people, to represent all the people. By marching towards that goal, in a messy fusion of self-interest, politics and idealistic progress, today McCain and Obama have something worthwhile in common.