McCain Needs 'knockout Blow' in Final Debate As Poll Ratings Collapse

John McCain yesterday threatened to up the ante in tonight's final televised presidential debate, which offers possibly his last chance to prevent a rout in November's election.

The Republican candidate said he would raise Barack Obama's links with Bill Ayers, one of the founders of an urban guerrilla group, as new polls showed McCain slipping further and Obama extending his reach into states normally considered solid Republican. US analysts and pollsters said that no one in recent modern history had been so far behind in mid-October and gone on to win an election.

The poll gap adds to pressure on McCain to deliver a knockout blow in tonight's 90-minute debate at Hofstra University in Hempstead, New York, the last of three.

McCain was lackluster in the first two, drawing the first and losing the second.

The Republican, who avoided "going negative" in the earlier debates, told a Chicago radio station yesterday that he was likely to raise the issue of Ayers, now a professor in Chicago who was with the Weathermen, a group responsible for a series of bombings in the US in the 1970s.

McCain said that he had been goaded into doing so by Obama. After the debate last week in Nashville, Tennessee, Obama noted that he had not had the courage to raise Ayers with him face to face, even though the McCain campaign had been relentlessly pursuing the issue each day.

McCain said yesterday that Obama's remarks "probably ensured" that he would bring up Ayers. "I was astonished to hear him say that he was surprised I didn't have the guts," McCain said.

His campaign team is mounting a relentlessly negative campaign to try to discredit Obama, seen as the only realistic opportunity left for turning the election.

Some of his team argue that the attacks on the links with Ayers have been ineffective and that McCain should bring up the Democratic candidate's association with his former pastor, the Reverend Jeremiah Wright, which McCain has resisted so far.

David Plouffe, Obama's campaign manager, yesterday distributed a video through the internet criticising McCain's team and associated groups for putting out what he described as "vile" adverts full of lies about Obama's policies on abortion, sex offenders and guns. Plouffe predicted that Republican groups would spend millions more on such ads as the election draws closer.

Negative campaigning, effective in previous elections, has so far failed to provide traction for McCain, partly because the electorate is almost exclusively focused on the impact of the financial crisis on their lives.

McCain yesterday set out a $52.5bn (£30bn) economic plan, his most detailed since the financial crisis began, to try to alleviate the plight of working families struggling with job losses, mortgage problems and squeezed pensions. This included buying up mortgages for families in danger of defaulting, offering lower taxes for people over 59 who need to dip into retirement funds to see them through the crisis and scrapping for the next two years tax on unemployment benefit.

"What we need to see now is swift and bold action to lead this country in a new direction," McCain told supporters in Blue Bell, Pennsylvania.

His plan came a day later than intended, indicating disarray inside his campaign team in the face of Obama's increasing poll leads. By delaying, McCain was beaten to the draw by Obama, who released his own economic proposals on Monday.

One of McCain's advisers, Douglas Holtz-Eakin, yesterday disputed talk of infighting and said despite reports that McCain was to announce his new economic policies on Monday, the plan had always been to unveil them yesterday.

Polls out yesterday showed Obama was winning the economic argument among independent voters who will decide the election and has extended his lead in states previously considered swing states or even safe Republican states.

The Quinnipiac University Polling Institute yesterday released its latest polls that put Obama on 52% to McCain's 43% in Colorado, on 55% to McCain's 37% in Michigan, and on 51% to McCain's 43% in Minnesota and Wisconsin.

"Those margins may be insurmountable barring a reversal that has never been seen before in the modern era, in which polling monitors public opinion throughout the campaign," said Peter Brown, at the Connecticut-based institute.

"The only possible bright spot for Senator McCain, and you would need Mary Poppins to find it in these numbers, is that he is holding roughly the same portion of the Republican vote. But his support among independent voters, a group he says are key to winning ... has collapsed."

McCain's best chance of winning, he said, is a "knockout" in the final debate.

Obama has spent the last three days in Toledo, Ohio, focused entirely on practicing for the debate. McCain, by contrast, was having to fit in practice between campaigning in Virginia on Monday and in Pennsylvania yesterday, and was scheduled last night to attend a fundraising event with Wall St financiers.