Just days after urging Congress to set aside partisan politics to solve America's financial crisis by backing the US$700 billion (S$1 trillion) bailout plan, both candidates have unleashed new offensives.

In the final stretch before the Nov 4 election, Republican John McCain's camp has launched a bid to cast Democratic rival Barack Obama as a dangerous radical, while the latter has accused Mr McCain of scheming to deprive millions of Americans of life-saving health insurance.

On Saturday, Mr McCain's running mate Sarah Palin told supporters in Colorado that Mr Obama 'is someone who sees America, it seems, as being so imperfect that he's palling around with terrorists who would target their own country'.

She cited a New York Times story on Saturday that examined Mr Obama's relationship with University of Illinois Professor Bill Ayers, a former member of the Vietnam War-era militant Weather Underground organisation.

The Times concluded that the men - who both served on the board of a foundation in Chicago - were not close, and the Obama campaign described Mrs Palin's guilt-by-association attack as 'desperate and false' and 'gutter politics'.

The Illinois senator, meanwhile, accused Mr McCain of a 'radical' plan which would rob ordinary Americans of their health-care plans.

'He taxes health-care benefits for the first time in history; millions lose the health care they have; millions pay more for the health care they get; drug and insurance companies continue to make exorbitant profits; and middle-class families watch the system they rely on begin to unravel before their eyes,' Mr Obama said.

Mr Obama, who has told supporters he will continue to run a positive campaign, used a Virginia rally to note that his rival proposed to give families a tax credit of US$5,000 (S$7,210) towards paying for rocketing health-care costs.

But he then added: 'Like those ads for prescription drugs, you got to read the fine print... When you read the fine print, it's clear that Mr John McCain is pulling an old Washington bait and switch. It's a shell game.'

The message was backed up by a TV and radio advertising onslaught claiming that Mr McCain's policies would see 20 million Americans lose their employer-funded health insurance.

McCain spokesman Tucker Bounds wasted no time in responding to the allegation, saying: 'Mr Barack Obama is lying to voters... It's a bald-faced lie.'

On Friday, top McCain adviser Greg Strimple promised a 'very aggressive last 30 days' of campaigning to erode Mr Obama's growing lead in the polls.

Following Friday's approval of the financial rescue plan, Mr Strimple told reporters: 'We are looking forward to turning a page on this financial crisis and getting back to discussing Mr Obama's aggressively liberal record and how he will be too risky for Americans.'

Mr McCain himself on Friday told supporters in Colorado: 'I guarantee you, you're going to learn a lot about who's the liberal and who's the conservative, and who wants to raise your taxes and who wants to lower them.'

AGENCE FRANCE-PRESSE, REUTERS