Washington - In the end, the choice of his running mate said more about Senator John McCain and his image of himself than it did about Sarah Palin, the little-known governor of Alaska whose selection has shaken up the presidential race.

    For weeks, advisers close to the campaign said, Mr. McCain had wanted to name as his running mate his good friend Senator Joseph I. Lieberman of Connecticut, the Democrat turned independent. But by the end of last weekend, the outrage from Christian conservatives over the possibility that Mr. McCain would fill out the Republican ticket with Mr. Lieberman, a supporter of abortion rights, had become too intense to be ignored.

    With time running out, and after a long meeting with his inner circle in Phoenix, Mr. McCain finally picked up the phone last Sunday and reached Ms. Palin at the Alaska State Fair. Although the campaign's polling on Mr. McCain's potential running mates was inconclusive on the selection of Ms. Palin - virtually no one had heard of her, a McCain adviser said - the governor, who opposes abortion, had glowing reviews from influential social conservatives.

    Mr. McCain was comfortable with two others on his short list, Gov. Tim Pawlenty of Minnesota and former Gov. Mitt Romney of Massachusetts. But neither was the transformative, attention-grabbing choice Mr. McCain felt he needed, top campaign advisers said, to help him pivot from his image as the custodian of the status quo to a change agent like his Democratic rival, Senator Barack Obama.

    Not least, Mr. Obama's decision to pass over Senator Hillary Rodham Clinton as his running mate opened the possibility for Republicans to put a woman on the ticket and pick off some of Mrs. Clinton's supporters.

    At 11 a.m. on Thursday, at the McCain vacation compound near Sedona, Ariz., Mr. McCain invited Ms. Palin to join him on the ticket. He hardly knew her, and she had virtually no foreign policy experience, but Ms. Palin was a "kindred spirit," a McCain adviser said. Mr. McCain was betting, the adviser said, that she would help him reclaim the mantle of maverick that he had lost this year.

    The selection was the culmination of a five-month process, described by Mr. McCain's inner circle and outside advisers in interviews this past weekend, and offers a glimpse into how Mr. McCain might make high-stakes decisions as president.

    At the very least, the process reflects Mr. McCain's history of making fast, instinctive and sometimes risky decisions. "I make them as quickly as I can, quicker than the other fellow, if I can," Mr. McCain wrote, with his top adviser Mark Salter, in his 2002 book, "Worth the Fighting For." "Often my haste is a mistake, but I live with the consequences without complaint."

    Mr. McCain began the search for a running mate shortly after he secured the Republican nomination, with some 40 names on a list. By early spring he had cut it to 20, including, a top adviser said, at least five women: Ms. Palin; Meg Whitman, the former chief executive of eBay; Secretary of State Condoleezza Rice; Carleton S. Fiorina, the former chief executive of Hewlett-Packard; and Senator Kay Bailey Hutchison, Republican of Texas.

    Mr. McCain cast the process, at least in those days, as orderly and said that the last thing he wanted was the kind of rushed decision that President George Bush had made in 1988 in selecting his running mate, Dan Quayle, then a senator from Indiana.

    But it was not until the last few weeks that Mr. McCain winnowed his list to five or six finalists. They included, a McCain adviser said, Mr. Pawlenty, Mr. Romney, Mr. Lieberman, Ms. Palin and Tom Ridge, the former governor of Pennsylvania who also supports abortion rights. Ms. Palin, unlike the others, was barely mentioned in news media speculation.

    The finalists, including Ms. Palin, were vetted, a campaign adviser said, and Mr. McCain then asked his inner circle - Mr. Salter, Rick Davis, Steve Schmidt and Charlie Black - to provide him with assessments of each. "He said, ‘Give me plusses and minuses on each of these people,' " Mr. Black said.

    One of Mr. McCain's closest friends, Senator Lindsey Graham, Republican of South Carolina, weighed in as well, pushing so hard for Mr. Lieberman - Mr. McCain, Mr. Graham and Mr. Lieberman are longtime traveling companions - that he vexed some of the other advisers. Others in the inner circle favored Mr. Pawlenty or Mr. Romney. Ms. Palin had no strong advocates in the group, an outside adviser said, but she had no detractors, either.

    Last Sunday, 24 hours after Mr. Obama announced his running mate, Senator Joseph R. Biden Jr. of Delaware, Mr. McCain met with his senior campaign team at the Ritz-Carlton Hotel in Phoenix. By then, campaign advisers said, the group had long decided that Mr. McCain's "experience versus change" argument against Mr. Obama had run its course, to the extent that it had worked at all.

    At the same time, Mr. Obama's coming acceptance speech before a stadium of about 80,000 people (and what turned out to be a television audience of nearly 40 million) loomed large. As much as the campaign was publicly dismissing Mr. Obama as a celebrity in a rock-star setting, the concern was that his command of such a large crowd on the last night of the Democratic convention would give him the aura of a president.

    In any case, one campaign adviser said, Mr. McCain hated running as the wizened old hand of experience. Despite his embrace this year of President Bush and many of the administration's policies, Mr. McCain, a campaign adviser said, still saw himself as the maverick who delighted in occasionally throwing political grenades at his own Party.

    Ms. Palin, and not Mr. Pawlenty or Mr. Romney, would reinforce Mr. McCain's self-image, an adviser said. She had a reputation as a reformer in Alaska, she hunted and fished, and she had once belonged to a union. Just as crucial, Ms. Palin, 44, was beloved by the party's religious base but did not come off as shrill. "She's conservative," Mr. Black said, "but she's not an ideologue."

    After Mr. McCain contacted Ms. Palin, Mr. Schmidt and Mr. Salter met with her on Wednesday in Flagstaff, Ariz. It was not until the following morning that she traveled to Sedona to meet with Mr. McCain, who then sat down with her for his only interview of a potential running mate.

    Within hours if not minutes after the interview was concluded, Ms. Palin had the job.

    Over the next weeks, Ms. Palin will be prepared by Mr. McCain's foreign policy staff, led by Randy Scheunemann, for the vice-presidential debate with Mr. Biden, chairman of the Senate Foreign Relations Committee, who moves easily among heads of state.

    Introducing Ms. Palin at a rally Saturday in Washington, Pa., Mr. McCain praised her and spoke about her selection.

    "You know, I had a lot of good people to choose from, and I want to thank Mitt Romney and Mike Huckabee and Fred Thompson and Rudy Giuliani," said Mr. McCain, referring to his rivals for the Republican nomination. "And," he added, "it's with great pride and gratitude I tell you I have found the right partner to help me stand up to those who have corrupted Washington."

    For her part, Ms. Palin still sounded surprised to have been picked. "Well, I know that when Senator McCain asked me to be his running mate, he had a short list of highly qualified men and women," she said. "To have made that list at all was a privilege. And to have been chosen, it brings a great challenge.

    "I know that it will demand the best that I have to give, and I promise nothing less."

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    Elisabeth Bumiller reported from Washington, and Michael Cooper from Pittsburgh and Washington, Pennsylvania.