Obama has climbed in Pennsylvania polls by working themes of economic populism, and Clinton's 60-second radio ad took aim at his TV commercial that says he doesn't "take money from oil companies."

"What he doesn't tell you is that no candidate does. They can't," the announcer in the Clinton ad states.

"According to the Annenberg Center's FactCheck.org, it's been against the law for companies to donate to candidates for a hundred years."

Corporate contributions are indeed prohibited by law, but FactCheck.org's critique of the Obama ad went beyond that observation.

Calling the Obama ad "a little too slick," FactCheck noted that the Obama campaign has accepted $213,000 from employees of oil companies and their spouses, and that two oil-company executives are Obama "bundlers" - fundraisers who have collected more than $50,000 for the campaign.

Obama's media consultant David Axelrod said yesterday that the ad referred to Obama's refusal to accept money from political-action committees.

He said contributions from oil-company employees and fundraising by the two executives, George Kaiser, chairman of Oklahoma-based Kaiser-Francis Oil Co., and Robert Cavnar, president of Milagro Exploration, don't refute Obama's claim in the ad.

"If they were doing it on behalf of their corporations, that would be the case," Axelrod said. "That's not what they were doing."

Clinton communications director Howard Wolfson said yesterday he would not rule out future TV ads attacking Obama.

Clinton's double-digit lead in state polls has slipped in recent weeks under the onslaught of a $6 million Obama ad campaign and energetic campaigning throughout the state.

Obama held town meetings yesterday in packed gyms at great Valley High School, in Malvern, and at Truman Senior High, in Levittown, stressing some of the same economic themes that Clinton has emphasized.

Obama spoke to cheering crowds and took questions that he noted had not been "scripted," a point demonstrated by one woman in Levittown.

Janet Cooper, 54, of Margate N.J., noted that Trumpets, a magazine published by Obama's Chicago church, once gave an award to Louis Farrakhan. Obama had criticized the award and said it was an example of the differences between him and the Rev. Jeremiah Wright, his former pastor.

"How can any praise for an anti-Semitic demagogue be considered a minor difference?" she asked. The question drew a few catcalls. Obama said he thought it a fair question. He said his criticism of the award for Farrakhan was a major difference, not a minor difference as Cooper had said.

"I've been very clear about saying that was wrong," Obama said. "No one has spoken out more clearly on the issue of anti-Semitism than I have. I have such strong support in the Jewish community in Chicago because they know this."

Cooper later said, "These are questions he needs to answer."

Cooper said she voted for Clinton in the New Jersey primary, but would support Obama over McCain in a general election.

In his speech, Obama repeated campaign promises to provide tax cuts to the middle class, more grants for college students, and new job opportunities.

"If we can afford to spend $10 billion a month in Iraq, we can afford to spend $10 billion a month in the United States of America putting people back to work," Obama said. "I want to create new job opportunities, new jobs, by investing in green technology."

In Malvern, Obama turned his fire not on Clinton, but on Republicans, whose economic policies he said had "excused and even embraced an ethic of greed, corner-cutting, and insider dealing that's distorted our economy.

"It's the story of the American dream slipping away," Obama said. "It's not an accident. It's the consequences of a tired and cynical economic philosophy that has failed the American people." *