Kerry hopes to maintain his rise from political ashes in Phoenix

With the latest polls placing them in a statistical tie, George Bush aimed fresh verbal attacks at his challenger John Kerry yesterday as he campaigned ahead of tonight's third and final debate.

With the latest polls placing them in a statistical tie, George Bush aimed fresh verbal attacks at his challenger John Kerry yesterday as he campaigned ahead of tonight's third and final debate.

In a final burst of allegations, Mr Bush said Mr Kerry would be forced to raise taxes in order to pay for his domestic proposals. He also continued to hurl the apparently unpalatable "l" word at his opponent, saying that while Mr Kerry was trying to cover his tracks he remained a "confirmed" liberal.

"I'm on my way to Arizona for the final debate. Those debates have highlighted the clear differences between the senator and me, ranging from jobs to taxes to health care and the war on terror. Much as he's tried to obscure it, on issue after issue, my opponent has showed why he has earned his ranking as the most liberal member of the United States Senate," said Mr Bush, speaking in Colorado Springs, Colorado before he made his way to a Republican fundraiser in Phoenix, Arizona.

While Mr Kerry was not campaigning yesterday, instead using the time to prepare for tonight's debate, his campaign was quick to fire back at the president's comments.

A spokesman, Phil Singer, said that Mr Bush's criticisms of Mr Kerry's domestic programmes were based on misleading studies.

"Over the past four years, we've seen health care in this country deteriorate into a crisis, costs have hit record levels, millions of people have lost their coverage and John Kerry has a plan to deal with those issues," he said.

Polls show Mr Bush and Mr Kerry in a mathematical tie as they prepare for what could be a crucial debate tonight on domestic issues at Arizona State University in the city of Tempe.

A Gallup poll taken for CNN and USA Today placed Mr Kerry on 49 points and Mr Bush on 48, while a poll conducted for Reuters by Zogby placed the two men on 45 points each.

As the polls have narrowed and hardened, campaigning by the two candidates and their parties has become increasingly barbed: in addition to Mr Bush's "liberal" accusations, Mr Kerry on Monday sought to tie the current record oil prices to Mr Bush's supporters in the energy industry.

"[The record price] means a lot more profit for this president's friends in the oil industry. But for most middle class Americans, the Bush tax increase is a tax increase that they can't afford," said Mr Kerry, campaigning in New Mexico, one of a dozen or so battleground states.

The debate in Arizona will focus largely on domestic issues, following the first debate in Florida which addressed foreign policy and the second encounter - a so-called "town hall" debate - in Cleveland, in which members of the audience were invited to ask questions of the candidates.

Mr Kerry, generally reckoned to have the better grasp of policy detail during the previous two debates, will be looking to capitalise tonight on an area on which Democrats have traditionally been considered stronger. Mr Bush's task has not been made easier by the latest monthly employment figures, released last Friday, which showed a smaller than anticipated number of jobs being created in September.

Mr Bush stressed the need for growth of community health centres to serve the poor and said that newly enacted legislation would revamp the healthcare available to senior citizens. He said Mr Kerry's proposed changes would put millions of people looking for health care into "a government programme".