“Senator Obama is an impressive speaker,” he said. “And the beauty of his words has attracted many people, especially among the young, to his campaign. I applaud his talent and his success. All Americans, all Americans should be proud of his accomplishment. I know I am.

“My concern with Senator Obama is on big issues, and small issues, what he says and what he does are often two different things. And that he doesn’t seem to understand that the policies he offers would make our problems harder, not easier to solve.”

Mr. McCain went on to criticize Mr. Obama for seeking pork-barrel spending (“nearly a million dollars for every working day he’s been in office”), accused him of wanting to raise taxes, painted him as an obstructionist on energy policy, rapped him for abandoning his pledge to take public financing, and criticized his Iraq policy.

Some of his lines of attack have been accused of being misleading. Mr. McCain, for instance, said Mr. Obama had voted in the Senate “for tax hikes that would have impacted those making $32,000 a year.” FactCheck.org, a nonpartisan Web site, said the vote was on a budget resolution to raise taxes on people making $41,500 a year; the $32,000 figure, it said, was the amount of taxable income those people had.

An advertisement criticized Mr. Obama for the high price of gas. “Who can you thank for rising prices at the pump?” an announcer intoned, as chants of “Obama, Obama” were heard.

Dan Schnur, who worked on Mr. McCain’s 2000 campaign and is the director of the Jesse M. Unruh Institute of Politics at the University of Southern California, said the McCain campaign seemed to be drawing on lessons from watching the Democratic primary fight between Mr. Obama and Senator Hillary Rodham Clinton.

“It wasn’t until the last weeks of the primary that Clinton and her campaign really took the gloves off on Obama, and as it happens it was too little, too late,” he said. “Obama is at his best when he talks from the mountaintop, and Clinton showed that the best hope for an opponent is to pull him back down to earth. McCain’s campaign quickly decided not to wait as long as she did.”