Sens. John McCain (R-Ariz.) and Barack Obama (D-Ill.) engaged in their final presidential debate Wednesday night at Hofstra University on Long Island, N.Y., a contest that focused largely on the economy and featured repeated efforts by the trailing McCain to attack Obama and his policies.

While Obama also threw some elbows, he often sought to steer the conversation back toward his proposals and describe himself as someone seeking an end to “tit for tat” partisanship.

McCain outlined what he said were “fundamental differences” between himself and his opponent.

Behind in polls both nationally and in key states, McCain’s performance amounted to an effort to rewrite the script of the election and jar voters’ perceptions of the two candidates on a range of fronts.

Obama maintained his composure throughout the onslaught, smiling broadly during McCain’s attacks as if bemused by what he considered absurd allegations. He associated McCain’s attacks with the reasons voters have become “cynical” about politics and promised to change “politics as usual.”

McCain sought to seize the reform mantle from Obama, saying he would change Washington, D.C., by forcing it from its free-spending ways.

“We’ve got to have a new direction for this country,” McCain said. “We have presided over the largest increase in government since the Great Society.”

Obama retorted by linking McCain’s voting record to the deficit runups under President Bush. He panned McCain’s plan to initiate an across-the-board spending freeze, saying it was too draconian.

Faced with weeks of relentless efforts by Obama to associate him with an unpopular administration, McCain tried to separate himself from President Bush, reciting a list of policies where he differed with the president. “Sen. Obama, I am not President Bush,” McCain declared. “If you wanted to run against President Bush, you should have run four years ago. I’m going to give a new direction to this economy in this country.”

But Obama quickly sought to paste together Bush and the GOP nominee.

“If I occasionally have 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,” Obama said.

McCain – more aggressively than in past encounters – sought to characterize Obama as a tax increaser, a protectionist and a supporter of increased spending, at one point even accidentally referring to Obama as “Sen. Government.” He described Obama’s health plan as “big government at its best.

A small-business man Obama recently encountered – christened by both candidates as “Joe the Plumber” – became a kind of everyman used by the two candidates to describe how their policies would affect a struggling entrepreneur.

McCain charged Obama would put Joe the Plumber out of business with higher taxes and new health insurance burdens. But McCain seemed somewhat stunned when he asked Obama how much Joe would be fined for not providing health care and Obama, addressing a presumably watching Joe, said “zero.”

But Obama frequently countered McCain with efforts to portray himself as someone who wants to heal divisions and reach across the aisle.

On a question about abortion, an issue that has sharply divided the electorate for decades, Obama offered a suggestion for where “we can find common ground,” saying people on opposite sides of the electorate could “come together” by trying to prevent unintended pregnancies.

The McCain campaign’s focus in recent days on Obama’s association with former Weather Underground member William Ayers was first alluded to by debate moderator Bob Schieffer of CBS. McCain pounced, saying, “We need to know the full extent of that relationship.”

Obama sought to describe the relationship as minimal and turn the allegations about Ayers – and about Obama’s association with the controversial group ACORN, or Association of Community Organizations for Reform Now – against McCain, saying it highlighted the incivility in politics and McCain’s desperation. “I think the fact that this has become such an important part of your campaign, Sen. McCain, says more about your campaign than it says about me,” Obama said.

McCain all but acknowledged Obama’s apparent victories in previous debates – if polls are to be believed – pointing to Obama’s “eloquence” but seeking to characterize it as deceptive glibness.