DENVER — Barack Obama's masterful acceptance speech before some 80,000 supporters in the Denver Broncos' stadium Thursday night was as impressive as one of John Elway's last-minute touchdown drives, but John McCain's go-for-broke choice of a running mate may be the political equivalent of a rally-killing interception.

The soon-to-be crowned Republican presidential nominee managed to steal the spotlight from his Democratic rival with his daring, and potentially risky, choice of Alaska Gov. Sarah Palin, while bringing Obama down from his Rocky Mountain high even before he had time to enjoy the rave reviews of his speech capping the Democrats' history-making convention.

Acting with the perfect timing of an all-pro cornerback, McCain surprised and shocked nearly everyone, maybe even himself, by celebrating his 72nd birthday by picking a 44-year-old political neophyte who could become the first woman vice president or prove to be a female Dan Quayle.

Apparently unmindful that the GOP's presidential campaign playbook calls for portraying Obama as too inexperienced to be president, the 72-year-old McCain — who has had serious health problems — chose someone who could soon stand a heartbeat from the presidency who's served less than two years as governor of a remote state with almost as many grizzlies, polar bears and caribou as people.

And while some senior congressional Democrats worry that Obama's biggest problem is that he hasn't been on the national stage long enough for voters to know who he is and what he stands for, some of their senior Republicans colleagues admitted they wouldn't recognize McCain's new running mate if she ran over them with her snowmobile.

Hail Mary pass
"I don't know much about her," Texas Sen. Kay Bailey Hutchison told CNN in what was hardly a Texas-sized endorsement. "I don't know Sarah Palin."

New York Sen. Chuck Schumer, who as chairman of the Democratic Senatorial Campaign Committee is trying to boost his party's razor-thin majority in the Senate this fall, used both sports and gambling terminology when asked about Palin, calling her selection "a Hail Mary pass" and "a real roll of the dice."

Palin's selection could turn out to be a masterstroke, luring women voters still outraged  that Obama chose Joe Biden instead of Hillary Rodham Clinton as his running mate, and calming the fears of conservative Republicans by choosing a woman whose conservative credentials are impeccable.

But it could also turn out to be a political misstep as big as Mount McKinley if Palin fails to demonstrate she's up to speed on critical issues like the economy — which McCain admits he doesn't understand — or on national security and military policy — which is one of Joe Biden's strengths, not to mention the fact he's been in the Senate since Palin was 18 years old. And she is hardly likely to help McCain carry one of the key states whose electoral votes he needs — one joke already making the rounds is that she was chosen because Alaska's three electoral votes match those of Biden's home state of Delaware.

In addition, although Palin has a reputation as a feisty reformer who hasn't hesitated to criticize two powerful Alaska Republicans, Sen. Ted Stevens and Rep. Don Young, for their involvement in political scandals — including one that got Stevens indicted — she is embroiled in a mini-scandal involving charges that one of her aides pressured state public safety officials to fire a state trooper who is the ex-husband of Palin's sister. 

Still, Palin, who recently said she doesn't even understand what a vice president does, could surprise everyone. As she demonstrated at the rally in Dayton, Ohio, where McCain introduced her, she is poised and articulate and clearly comfortable in her new role.

As veteran political operative Ted Van Dyk, a former aide to Vice President Hubert Humphrey, wrote in Crosscut, a Seattle on-line publication: "If  Palin is up to it, she should be a huge help to McCain. If not, McCain truly did blow the election… In the short term, McCain successfully changed the subject only hours after Democrats' rousing Denver triumph. He will be having us watch next week's Republican convention, if only to watch and learn more about Palin."