Palin, the Republican vice presidential candidate, launched the attack Saturday and repeated it Sunday, signaling a new strategy by John McCain's presidential campaign to go after Obama's character.
"The comments are about an association that has been known but hasn't been talked about," Palin said as she boarded her plane in Long Beach, Calif. "I think it's fair to talk about where Barack Obama kicked off his political career, in the guy's living room."
Later, at a fundraiser, Palin elaborated on her attack, claiming one of Obama's advisers had described Obama and Ayers as "friendly."
"In fact, Obama held one of his first meetings hoping to kick off his political career in Bill Ayers' living room," she told the crowd, which had just raised $2.5 million for the Republican party's McCain-Palin Victory 2008 fund.
At issue is Obama's association with Ayers. Both have served on the same Chicago charity and live near each other in Chicago. Ayers also held a meet-the-candidate event at his home for Obama when Obama first ran for office in the mid-1990s, the event cited by Palin.
In February, Obama strategist David Axelrod told the Politico Web site: "Bill Ayers lives in his neighborhood. Their kids attend the same school. They're certainly friendly, they know each other, as anyone whose kids go to school together."
But while Ayers and Obama are acquainted, the charge that they "pal around" is a stretch of any reading of the public record. And it's simply wrong to suggest that they were associated while Ayers was committing terrorist acts. Obama was 8 years old at the time the Weather Underground claimed credit for numerous bombings and was blamed for a pipe bomb that killed a San Francisco policeman.
At a rally in North Carolina, Obama countered that McCain and his campaign "are gambling that he can distract you with smears rather than talk to you about substance." The Democrat described the criticism as "Swiftboat-style attacks on me," a reference to the unsubstantiated allegations about 2004 Democratic nominee John Kerry's decorated military record in Vietnam.
During her stop in California, Palin was asked about an Associated Press analysis that said her charge about Ayers was unsubstantiated, a point made by other news organizations, and the criticism carried a "racially tinged subtext that McCain may come to regret."
"The Associated Press is wrong," Palin said, before arguing that the issue had not been adequately discussed.
In fact, Obama was questioned about Ayers during a prime-time Democratic debate against Sen. Hillary Rodham Clinton prior to April's Pennsylvania primary.
Palin, recharged after last week's debate against Democratic vice presidential nominee Joe Biden, is animating the party's conservative wing with harsh attacks against Obama. She's courting high-dollar donors for campaign cash. And she is looking to wrestle away women and independent voters from the Democrats.
"The heels are on, the gloves are off," she declares, a threat delivered with a smile.
With that message, the campaign is sending her on a whirlwind tour of political trouble spots.
On Sunday, she was headed for a rally in Omaha, Neb., a defensive move in one of the two states in the nation that can split their electoral votes. Her visit illustrated the depth of worry within the McCain camp. Since 1964, all five of the state's electoral votes have gone to the Republican presidential candidate.
On Monday, she begins a two-day, event-packed tour of Florida that stretches from Naples in the South to Pensacola in the panhandle. North Carolina and Pennsylvania are next.
After a hold-your-ground debate performance last week, Palin is back to where she was after her show-stopping speech at the Republican convention a month ago - the top draw in the McCain-Palin ticket.
About 10,000 people came to her rally Saturday in the Los Angeles suburb of Carson. She raised $2 million in one California fundraiser for the McCain-Palin Victory 2008 fund. She's getting the star treatment from the likes of Grammy winner Vikki Carr and actor Robert Duvall.
She's still the carefully handled national politics greenhorn. Reporters traveling on her plane are kept at a distance. At fundraising events she doesn't take questions in public from donors, as McCain does. Contributors greet her privately before she allows the press in for her stump speech.
She brushes off some of her criticism as if it were lint on her jacket.
"People say that I speak too simply, or don't have quite the - I don't have my thesaurus in my back pocket all along through my speeches," she told donors in Englewood, Col. "Well, I don't have time for that."
On Sunday she told donors she had been asked why she had done so poorly in interviews with CBS News anchor Katie Couric. "You know what I should have said?" she joked. "It's job security for Tina Fey" - the woman who impersonates her on "Saturday Night Live."