"She's exactly who I need. She's exactly who this country needs to help me fight the same old Washington politics of 'Me first and country second,' " McCain declared as the pair stood together for the first time at a boisterous rally in Ohio just days before the opening of the party's national convention.
Palin, the first Republican woman on a presidential ticket, promised: "I'm going to take our campaign to every part of our country and our message of reform to every voter of every background in every political party, or no party at all."
"Politics isn't just a game of competing interests and clashing parties," added Palin, 44, who has built her career in large measure by challenging fellow Republicans.
In the increasingly intensive presidential campaign, McCain made his selection six days after his Democratic rival,, named Sen. Joseph Biden of Delaware, as his No. 2 on the ticket.
"This is John McCain the fighter pilot," said CBS News chief Washington correspondent Bob Schieffer when he heard the news. "He is willing to take a risk and put it all up on the line. I think the Republican base will be pleased by this."
"This the most out of the box pick in a very long time," added CBS News senior political correspondent Jeff Greenfield. "It says to me that the McCain camp believes the democratic convention was a success for the Democrats, they cannot afford to play it safe."()
The contrast between the two announcements was remarkable - Obama, 47, picked a 65-year-old running mate with long experience in government and a man whom he said was qualified to be president. The timing of McCain's selection appeared designed to limit any political gain Obama derives from his own convention, which ended Thursday night with his nominating acceptance speech before an estimated 84,000 in Invesco Field in Colorado.
Public opinion polls show a close race between Obama and McCain, and with scarcely two months remaining until the election, neither contender can allow the other to jump out to a big post-convention lead.
On his 72nd birthday, McCain chose Palin, a woman younger than two of the Arizonan's seven children and a person who until recently was the mayor of small-town Wasilla, Alaska and has been governor less than two years. He settled on her six months after first meeting the governor and following only one phone call between them last Sunday and a single face-to-face meeting Thursday, according to a timeline provided by his campaign.
(Learn more about Sarah Palin.)
The Obama campaign immediately questioned whether she would be prepared to step in and be president if necessary.
"Today, John McCain put the former mayor of a town of 9,000 with zero foreign policy experience a heartbeat away from the presidency," Adrianne Marsh, a spokeswoman for Obama, said in a written statement.
While members of his campaign staff attacked the pick, Obama praised Palin, calling her a "compelling person with a terrific personal story," reports CBS News correspondent Dean Reynolds
Obama placed a short phone call to Palin Friday afternoon to congratulate her.
President Bush complimented McCain for "an exciting decision."
"Governor Palin is a proven reformer who is a wise steward of taxpayer dollars and champion for accountability in government," a presidential statement said. "By selecting a working mother with a track record of getting things done, Senator McCain has once again demonstrated his commitment to reforming Washington."
Sen. Hillary Rodham Clinton, who came so close to being the first major party woman presidential candidate, said in a statement: "We should all be proud of Gov. Sarah Palin's historic nomination, and I congratulate her and Sen. McCain. While their policies would take America in the wrong direction, Gov. Palin will add an important new voice to the debate."(Read more reaction to the Palin pick)
"It definitely reflects a decision on two fronts," said CBS News political analyst Dan Bartlett, a former adviser to President Bush. "One that with the departure of Hillary Clinton from the race that this is an opportunity for McCain to make even more headway to a key voting block."
"Second, they're aiming to reinforce message of reform. Palin is someone who has made a mark on both the state of Alaska and nationally as someone who has taken on ethics reform boldly," Bartlett added. "The McCain campaign seems to believe those two qualities will more than make up for her lack of national exposure."
On the flipside, CBS News political analyst Joe Trippi, a former Democratic strategist, said: "If he's going to argue she's ready, he's taken away the argument that Barack Obama isn't."
Palin's name had not been on the short list of people heavily reported upon by the news media in recent days, and McCain's decision was a well-kept secret until just a couple hours before Friday's rally.
McCain's campaign said that Palin and a top aide met with senior McCain advisers in Flagstaff, Ariz., on Wednesday night. The next morning, the campaign said McCain formally invited Palin to join the ticket on the deck of McCain's home near Sedona, Ariz., and later Thursday the governor flew to Middletown, Ohio, with staff to await Friday's event in Dayton.
Describing the process that led to her selection, Palin told reporters she'd received word that she was McCain's choice on Thursday and had met privately with him that day to discuss it. She spoke briefly as the two running mates surprised shoppers at the Buckeye Corner in Columbus, Ohio, where they purchased Ohio State University sports memorabilia. McCain and Palin started a bus tour across Ohio and to Pittsburgh, where they will hold a campaign rally Saturday. Ohio and Pennsylvania are two states that figure prominently in who wins the election this fall.
Asked why McCain chose her, his campaign manager Rick Davis said, "Part of it is personal fit."
"He sees Sarah, Governor Palin, as the future of the party," he added. "These are people he'd like to elevate in that regard. reformers."
Sharyl Odenweller, a retired teacher from Delphos, Ohio who was visiting the store, said she was pleased that McCain had chosen a woman and someone "very pro life." But, Odenweller also said, "I'd like to know more about her experience. If something happened to him, would she be qualified to step into the presidency?"
With his pick, McCain passed over more prominent contenders like former Massachusetts Gov. Mitt Romney and Minnesota Gov. Tim Pawlenty, as well as others such as former Pennsylvania Gov. Tom Ridge, whose support for abortion rights might have sparked unrest at the convention that opens Monday in St. Paul, Minn.
A self-styled hockey mom and political reformer, Palin became governor after ousting a state chief executive of her own party in a primary.
Her political career started with the PTA, reports CBS News correspondent Chip Reid. She quickly moved up to the town council, then the mayor's office of Wasilla, a suburb of Anchorage. Along the way she revived her old basketball nickname, Sarah "Barracuda," given for her aggressive style and willingness to take on corruption in a state notorious for its wild west ethics.
More recently, she has come under the scrutiny of an investigation by the Republican-controlled legislature into the possibility that she ordered the dismissal of Alaska's public safety commissioner because he would not fire her former brother-in-law as a state trooper.
Palin has a long history of run-ins with the Alaska GOP hierarchy, giving her genuine maverick status and reformer credentials that could complement McCain's image.
Palin is also celebrating her 20th wedding anniversary, reports CBS Evening News anchor Katie Couric.
Her husband, Todd Palin, is part Yup'ik Eskimo, and is a blue-collar North Slope oil worker who competes in the Iron Dog, a 1,900-mile snowmobile race. The couple lives in Wasilla. They have five children, the youngest of whom was born in April with Down syndrome.
It was discovered during pre-natal testing, but the fierce opponent of abortion said she sees only perfection when she looks at her son, reports Couric. Her oldest son, 19-year-old Track, enlisted in the army a year ago and will be deployed to Iraq next month.