DENVER -- John McCain's risky choice of Gov. Sarah Palin gives him a running mate who doubles down on his maverick image, may appeal to "hockey moms" and other women, and counters Barack Obama's aura of new-generation change. But he may have undercut his best attack on the Democrat.

She is younger and less experienced than the first-term Illinois senator, and brings an ethical shadow to the ticket. 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.

"On his 72nd birthday, is this really the one-heartbeat-away he wants to put in the White House?" said Rep. Rahm Emanuel, the No. 3 Democrat in the House. "What does this say about his judgment?"

It says that McCain wanted to add a reform-minded politician to his ticket, and an abortion opponent to boot. It says he needs more women to back him over Obama, who just welcomed a passel of Hillary Clinton voters into his fold but remains shaky with white males. And, finally, it's a recognition of how vulnerable McCain is despite polls showing it's close.

He put his money down on a darkhorse to try to change the race.

A suburban mother and PTA member who described her fisherman husband as a proud union member and "champion snow machine racer," Palin brings to the ticket the blue-collar, everyday-American qualities that Sen. Joe Biden brought last week to Obama's ticket -- with a distinctively Alaskan twist.

The pick earned McCain praise Friday from evangelicals and other social conservatives who have been skeptical of him. "Conservatives will be thrilled with this pick," said Greg Mueller, a conservative GOP strategist.

The price for that support could be high. Palin's lack of experience undercuts GOP charges that Obama is not ready to be commander in chief. McCain said in April that he was determined to avoid a pick like Dan Quayle, the little-known Indiana senator whom George H.W. Bush put on his ticket in 1988. The choice proved embarrassing.

Quayle "had not been briefed and prepared for some of the questions," McCain said while discussing his vice presidential search. He was clearly aware that, as a septuagenarian, the decision he made about a running mate would be "of enhanced importance."

Four months and one birthday later, McCain's announcement of Palin made clear the paucity of her experience.

"As the head of Alaska's National Guard and as the mother of a soldier herself," the statement said, "Gov. Palin understands what it takes to lead our nation and she understands the importance of supporting our troops."

It is true, as the statement said, that Palin has a record of bipartisan reform. She has a growing reputation as a maverick for bucking her party's establishment and Alaska's powerful oil industry. Palin campaigned on ethics reform in the 2006 GOP primary to defeat incumbent Gov. Frank Murkowski, who served 22 years in the U.S. Senate before winning the governor's seat in 2002.

"She's exactly who I need," said McCain, who passed over several more experienced candidates -- mostly men. "She's exactly who this country needs to help me fight the same old Washington politics of 'Me first and Washington second.' "

The campaign put out a statement saying what McCain did not: "She is ready to be president."

She has an ethical issue as well. Alaska lawmakers are investigating whether Palin abused her power in firing a public safety commissioner. Lawmakers say they want to know whether Palin was mad at the commissioner for not firing an Alaska state trooper who went through a messy divorce and ongoing child custody battles with Palin's sister.

Palin is 44, Obama 47. She served in her statehouse 20 months. Obama served in his statehouse for eight years. Obama and Palin are running less on their resumes than on they are on their promise. The promise of change and new politics.

The difference: Obama wants the top job, Palin the No. 2. But experience is something that matters to all voters -- whether Republican, Democratic or independent. And, as McCain has suggested himself, his 72nd birthday is a reminder that age matters, too.

• Ron Fournier has covered politics for The Associated Press for nearly 20 years.