HEMPSTEAD, N.Y. (AP) — John McCain sought to change the course of a campaign moving decidedly in Barack Obama’s direction Wednesday night in the third and final presidential debate.

With less than three weeks until the Nov. 4 election, the 90-minute debate focusing on the economic crisis offered the Republican senator from Arizona what could be one of his last big chances to persuade voters to give the race another look. Polls show Obama, the senator from Illinois, with a clear lead nationally and in several key battleground states.

McCain was keenly aware of the stakes he faced after two debates in which supporters suggested he was insufficiently forceful against Obama.

Over the weekend he promised to “whip” Obama’s “you know what,” and aides indicated McCain would criticize Obama on tax policy.

For months, McCain and his campaign have tried to convince voters that Obama is an inveterate tax raiser whose spending priorities on health care and other issues would mean higher taxes on people of all incomes. Obama has said he would raise taxes only on people making over $250,000 per year.

Obama strategist David Axelrod said Wednesday the Illinois senator would not offer new policy prescriptions in the debate but would try to keep the focus on his plans for improving the economy and creating jobs.

“We have always believed that as people came to know Sen. Obama – to see him, to hear him – that that would be helpful to his candidacy because he is a solid person with good ideas for how to bring about constructive change in this country,” Axelrod said.

McCain traveled to Long Island Wednesday afternoon from Manhattan, where he had headlined a $10 million fundraiser for the Republican National Committee Tuesday night. Obama flew in from Ohio, where he had stayed for several days of debate preparations. Both candidates separately toured the debate hall at Hofstra University.

The nationally televised forum was to focus on the economy and domestic policy, a timely topic as voters try to assess which candidate they most trust to handle the historic meltdown of U.S. financial markets. The two candidates were to be seated together at a table with CBS News anchor Bob Schieffer, the debate moderator.

The debates, while widely watched, have been panned by many critics for adhering to rules worked out between the two campaigns that limited interchange between the candidates and quashed follow-up questions by moderators. The format has allowed both Obama and McCain to rehash campaign talking points while largely avoiding direct answers to questions.