Republicansand questioned on Wednesday whether record matched his rhetoric as they sought to sow doubt about the Democratic presidential candidate.
Speaking to a rowdy crowd of supporters in this eastern Pennsylvania town, McCain and Palin both challenged Obama's campaign claims. Dismissing Obama as just "a guy who's just tried to talk his way into the White House," vice presidential candidate Palin said the Democrats' ideas are stale and dangerous.
"He's not willing to drill for energy, but he's sure willing to drill for votes," Palin said, eliciting cheers of "Drill, baby, drill" from the crowd, which often interrupted the candidates during their joint appearance.
McCain's remarks about Obama were interrupted with shouts of "socialist," "terrorist" and "liar." At another time, a man in the bleaches shouted "No more ACORN," referring to a group that registers poor voters.
"We've all heard what he's said. But it's less clear what he's done, or what he will do," McCain said.
The crowd replied with chants, "Nobama."
Similarly, Palin said there were too many questions about Obama's past: "John McCain didn't just come out of nowhere. The American people know John McCain."
Advisers say the Republican ticket will continue this forceful tone as the campaign enters its final month. Obama leads in national and state polls; McCain is looking for a way to change that.
"Which candidate's experience, in government and in life, makes him a more reliable leader for our country and commander in chief for our troops?" McCain said. "In short, who is ready to lead?"
McCain's speech centered on policies that would help the working class voters in this region where the race is close. Obama lost Pennsylvania's Democratic primary to Sen. Hillary Rodham Clinton and has struggled to connect with the white, working-class voters he once said cling to guns and religion in times of economic uncertainty.
"What Sen. Obama says today and what he has done in the past are often two different things," McCain said.
Citing taxes, health care and energy, McCain appealed to voters' pocketbooks and lingering doubts about Obama.
"Who is the real Sen. Obama?" McCain said, repeating a line he debuted on Monday in New Mexico, another state he needs to win White House. "Is he the candidate who promises to cut middle class taxes, or the politician who voted to raise middle class taxes?"