HEMPSTEAD, N.Y. - Republican John McCain made his most forceful assertion of independence from George W. Bush last night and used the final debate of the presidential calendar to deliver his most direct attack yet on Barack Obama's character and policies.
"Senator Obama, I am not President Bush," McCain said, sitting across a small table from his Democratic opponent. "If you wanted to run against President Bush, you should have run four years ago."
But Obama reiterated his campaign's central premise that the Republican nominee was offering a "third term" for Bush on the issues that have come to dominate the race.
"If I've occasionally mistaken your policies for George Bush's policies, it's because on the core economic issues that matter to the American people - on tax policy, on energy policy, on spending priorities - you have been a vigorous supporter of President Bush."
Meeting for a freewheeling 90-minute exchange just hours after another massive plunge in the stock market, with less than three weeks until Election Day, the two candidates clashed over whose tax plans would spur an economic recovery and create jobs, and traded accusations over whether attacks by both campaigns have been justified and relevant at a time of fiscal crisis.
The debate came to be dominated by "Joe the plumber," as the two candidates referred to Joe Wurzelbacher, an Ohioan who wanted to buy a plumbing company and confronted Obama at a weekend event near Toledo to complain that the Democrat's plan would raise his taxes and make it difficult for him to hire workers.
McCain invoked Wurzelbacher first, but both candidates referred to him throughout as an election-year everyman for a nation on the cusp of a potentially deep recession.
"What you want to do to Joe the plumber and millions more like him is have their taxes increased and not be able to realize the American dream of owning their own business," McCain told Obama.
Obama responded that Joe the plumber had been "watching some ads of Senator McCain's." While agreeing that he and McCain have a major difference on tax policy, Obama said his plan would not raise taxes on those earning less than $250,000. He also said that he has proposed giving business a $3,000-per-job tax credit for new hires.
McCain, who recent polls have shown lagging by growing margins, took the lead in outlining new areas of disagreement, often leaving Obama on the defensive. Twice McCain offered sarcastic praise for Obama's "eloquence" as he accused his opponent of obscuring his position on issues.
McCain repeatedly turned the conversation to the subject of free trade, a particularly controversial issue in Rust Belt manufacturing states like Ohio and Indiana, where the candidates are still battling.
McCain said that Obama's stated willingness to renegotiate the North American Free Trade Agreement could alienate Canada, and lead its government to export oil to countries other than the United States. "You don't tell countries you're going to unilaterally renegotiate agreements with them," McCain said.
He took issue as well with Obama's opposition to a bilateral free-trade agreement with Colombia, a policy Obama defended by criticizing the country's labor practices.
"Free trade with Colombia is something that's a no-brainer; maybe you ought to travel down there and visit them, and maybe you could understand it a lot better," McCain told Obama, who has never traveled to Latin America.
Obama answered, "I believe in free trade, but I also believe that for far too long, certainly during the course of the Bush administration with the support of Senator McCain, the attitude's been that any trade agreement is a good trade agreement."
The debate was the last of three between the candidates, whose fortunes have been diverging widely in recent polls. One released Tuesday by the New York Times and CBS News showed Obama with his broadest advantage yet: a lead of 53 percent to 39 percent among likely voters, bolstered by a recent surge in popularity among independents.
Both candidates said they lamented the campaign's bitter tone and accused the other of primary responsibility for it. McCain charged that Obama "didn't tell the American people the truth" by reversing a pledge to accept federal financing for his campaign. As a result, McCain alleged, Obama has had the resources to air more negative ads than any candidate since the 1970s.
Obama, in turn, charged that every McCain ad attacks him.
"Senator McCain's running a negative campaign versus one-third of mine," Obama said. "And 100 percent, John, of your ads - 100 percent of them - have been negative."
"That's not true," McCain interjected.
"A hundred - it is absolutely true," Obama said.
It was Obama who first raised the matter of William Ayers, a 1970s radical who cofounded a group that bombed government buildings. Obama's relationship with Ayers, now an education professor in Chicago, has been the subject of Republican ads and a recent charge from McCain's running mate, Sarah Palin, that Obama has been "palling around with terrorists." Obama said that the educational-policy board on which the two served included prominent Republicans, and that the two maintain no current political ties.
"Mr. Ayers is not involved in my campaign," Obama said. "He has never been involved in this campaign. And he will not advise me in the White House."
At another point, McCain emotionally protested a statement by civil rights leader Representative John Lewis, a Georgia Democrat who supports Obama. Lewis had objected to McCain supporters at rallies calling Obama a terrorist. Lewis said that it was reminiscent of racist taunts made during the civil rights movement by segregationist George Wallace, the former governor of Alabama.
"Congressman John Lewis, an American hero, made allegations that Sarah Palin and I were somehow associated with the worst chapter in American history: segregation, deaths of children in church bombings, George Wallace," McCain said. "That . . . that to me was so hurtful."
Obama, who said he was disturbed by reports of death threats directed at him from McCain's crowds, said he was not responsible for Lewis's remarks and thought the congressman "inappropriately drew a comparison between what was happening there and what had happened during the civil rights movement."
When McCain alleged that Obama had never challenged his own party, Obama was ready with a litany of positions as he boasted of his skill at standing up to fellow Democrats.
"The first major bill that I voted on in the Senate was in support of tort reform, which wasn't very popular with trial lawyers, a major constituency in the Democratic Party," Obama said.
"I support charter schools and pay-for-performance for teachers. Doesn't make me popular with the teachers union," he went on. "I support clean-coal technology. Doesn't make me popular with environmentalists."
The candidates differed on the merits of the 1973 Roe v. Wade decision, although each said he would not turn a potential Supreme Court nominee's position on abortion into a litmus test for the job.
"I would consider anyone in their qualifications," McCain said. "I do not believe someone who had supported Roe v. Wade would be part of those qualifications, but I would not impose any litmus test."