Republican vice presidential candidate Sarah Palin on Saturday accused Democrat Barack Obama of "palling around with terrorists" because of an association with a former '60s radical, stepping up an effort by John McCain's campaign to portray Obama as unacceptable to American voters. Palin's reference was to Bill Ayers, one of the founders of the group the Weather Underground. Its members took credit for bombings, including nonfatal explosions at the Pentagon and US Capitol, during the Vietnam War era. Obama, who was a child when the group was active, has denounced Ayers' radical views and activities. Palin told a group of donors at a private airport, "Our opponent ... is someone who sees America, it seems, as being so imperfect, imperfect enough, that he's palling around with terrorists who would target their own country." She also said, "This is not a man who sees America as you see America and as I see America." The Obama campaign called Palin's remarks offensive but not surprising in light of news stories detailing the McCain campaign's come-from-behind offensive. "What's clear is that John McCain and Sarah Palin would rather spend their time tearing down Barack Obama than laying out a plan to build up our economy," Obama campaign spokesman Hari Sevugan said in a statement. Palin, Alaska's governor, said that donors on a greeting line had encouraged her and McCain to get tougher on Obama. She said an aide then advised her, "Sarah, the gloves are off, the heels are on, go get to them." The escalated effort to attack Obama's character dovetails with TV ads by outside groups questioning Obama's ties to Ayers, convicted former Obama fundraiser Antoin "Tony" Rezko and Obama's former pastor, the Rev. Jeremiah Wright. Ayers is a professor at the University of Illinois at Chicago. He and Obama live in Chicago's Hyde Park neighborhood and served together on the board of the Woods Fund, a Chicago-based charity that develops community groups to help the poor. Obama left the board in December 2002. Obama was the first chairman of the Chicago Annenberg Challenge, a school-reform group of which Ayers was a founder. Ayers also held a meet-the-candidate event at his home for Obama when Obama first ran for office in the mid-1990s. In an interview with CBS News earlier in the week, Palin did not name any newspapers or magazines that shaped her view of the world. On Saturday, she cited a New York Times story that detailed Obama's relationship with Ayers. Summing up its findings, the Times wrote: "A review of records of the schools project and interviews with a dozen people who know both men, suggest that Mr. Obama, 47, has played down his contacts with Mr. Ayers, 63. But the two men do not appear to have been close. Nor has Mr. Obama ever expressed sympathy for the radical views and actions of Mr. Ayers, whom he has called 'somebody who engaged in detestable acts 40 years ago, when I was 8."' Earlier Saturday, Palin spent 35 minutes at a diner in Greenwood Village where she met with Blue Star Moms, a support group of families whose sons or daughters are serving in the armed forces. Reporters were allowed in the diner for less than five minutes before being ushered out by the campaign. Palin, whose 19-year-old son, Track, headed for deployment to Iraq last month as a private with an Army combat team, was overheard at one point commiserating with one of the mothers: "Any time I ask my son how he's doing, he says, 'Mom, I'm in the Army now."'