ST. LOUIS (AP) — John McCain's campaign aches needed a tonic.

On a day when he abandoned the fight with rival Barack Obama in the battleground state of Michigan and national polls showed him trailing overall, running mate Sarah Palin put on a debate performance that soothed the pain.

Going up against Democratic running mate Joe Biden, the Alaska governor offered reassurance to Republicans and conservatives unnerved by her lack of national experience and her faltering conduct in two recent TV network interviews.

She winked and smiled and shrugged through a litany of grievances against Obama on taxes, the war in Iraq and energy. She jotted down notes, glancing at them from behind her lectern as she checked off the points of her replies. And she made a case to the middle class, offering a populist answer to the cause of the current housing crisis.

"Darn right it was the predator lenders, who tried to talk Americans into thinking that it was smart to buy a $300,000 house if we could only afford a $100,000 house," she said.

But even as Palin reversed some of the harm she had caused herself, Biden was meeting his own tasks as well. Time and again, the veteran Delaware senator tied McCain to unpopular President Bush and managed to connect with the audience on a personal level as much as he did on policy points.

Disciplined, he defended Obama from attacks, but refused to engage Palin in a tit-for-tat exchange.

By the end of the night, a CNN poll found that a majority of debate watchers believed Biden had won, as did a CBS poll of undecided voters.

Earlier in the day, the McCain campaign was forced to concede that it was stopping its advertising and scaling back staff in Michigan, a crucial state in the race. Palin, winner or not, simply helped by not hurting McCain any further.

"Her performance had unlimited downside potential but probably has a limited upside," said Todd Harris, who worked on McCain's 2000 presidential campaign and advised Fred Thompson's presidential bid this year. "I doubt that this will change the dynamics of the race, but it certainly might help stop some of the bleeding."

Compared to the fairly stoic, policy driven presidential debate last week, this encounter was a duel of personalities. Where Obama is cool and reserved, Biden can be emotional and bombastic. And where McCain debated firmly but dispassionately, Palin wielded her attack lines almost cheerfully.

The debate showcased two sides of Biden — the master senator invoking long gone colleagues such as Mike Mansfield and Jesse Helms and rattling off foreign policy details with ease, and the "just Joe" image he has tried to cultivate on his daily train commute between Washington and Wilmington, Del.

Biden's voice broke as he spoke of his son and McCain's son being deployed to war. Beau Biden, the Delaware attorney general, is scheduled to fly to Iraq with his National Guard soon. Biden plans to attend his deployment ceremony Friday in Delaware.

And both Biden and Palin sought to appeal to independent and undecided voters by speaking the language of middle America, though both have long stopped leading average middle class lives.

"I don't think either one of them was going to conceded that the other had more middle class roots," said Bill Carrick, a California Democratic consultant and veteran of past presidential campaigns.

Take Biden's personal recollection: "I understand what it's like to sit around the kitchen table with a father who says, 'I've got to leave, champ, because there's no jobs here. I got to head down to Wilmington. And when we get enough money, honey, we'll bring you down.'"

And Palin, a self-described hockey mom, was speaking of another mom cohort when she said: "Go to a kid's soccer game on Saturday, and turn to any parent there on the sideline and ask them, 'How are you feeling about the economy? And I'll bet you, you're going to hear some fear in that parent's voice.'"

The debate format suited both candidates' styles. Confined to 90-second responses, Biden's tendency to overspeak was held in check. Palin also seemed to find comfort in the time limits which allowed her to make her points succinctly on less familiar ground and to use the two-minute rebuttal period to occasionally expand on a previous point.

"I would like to respond about the tax increases," she said when the topic turned to subprime mortgages. "I want to go back to the energy plan," she said at another point, sidestepping another discussion of taxes.

It was the first time both candidates had met. "Hey, can I call you Joe?" Palin asked as they were introduced. "Governor, it really was a pleasure getting to meet you," Biden said as the debate wrapped up.

Given Palin's performance, the debate begged one last question: What does Tina Fey do now?