Virginia - US President Barack Obama set an aggressive tone on Friday ahead of his final debate with White House challenger Mitt Romney, accusing the Republican of suffering from policy "Romnesia".
One night earlier, both men had traded light-hearted banter at a charity dinner but on Friday the barbs turned nasty, with the Democratic incumbent taunting Romney's efforts to tack to the centre as polling day looms.
"Mr Severely Conservative wants you to think he was severely kidding about everything he said over the last year," Obama said at a rally attended by some 9 000 people at a university campus outside Washington.
The Obama camp's previous bid to skewer Romney with insulting tags - such as pushing the term "Romney Hood" to tarnish his tax policies - have done nothing to protect the president's shrinking poll lead.
But, with the pair's last head-to-head debate on Monday and less than three weeks until election day on 6 November, the campaign returned to its tried and tested formula of branding Romney an untrustworthy flip-flopper.
"I mean, he's changing up so much and backtracking and sidestepping, we've got to name this condition that he's going through. I think it's called 'Romnesia.' That's what it's called," Obama told the crowd.
Romney's camp dismissed the taunt as a "new gimmick for the day", but the image of Romney as a flip-flopper, one that his fellow conservatives have hit him with the past, might yet gain traction with undecided voters.
One source that definitely does not back the multimillionaire private equity baron is The Salt Lake Tribune, the local paper in the home city of Romney's Mormon faith, albeit a liberal one that endorsed Obama in 2008.
In an editorial, the paper lavished praise on Romney for saving the city's 2002 Winter Olympics, but said his subsequent courting of the right-wing Tea Party movement and refusal to detail his tax plan should rule him out.
"Romney has raised the most frequently asked question of the campaign: 'Who is this guy, really, and what in the world does he truly believe?'" it said.
"Politicians routinely tailor their words to suit an audience. Romney, though, is shameless, lavishing vastly diverse audiences with words, any words, they would trade their votes to hear," it declared.
"Therefore, our endorsement must go to the incumbent... The president has earned a second term."
While Obama was addressing crowds in Virginia, a state he won narrowly in 2008 but where Romney is making up ground, Romney flew to the biggest battleground of them all, Florida, for a rally with running mate Paul Ryan.
Obama won both states in 2008, but as a measure of the tightness of this year's contest, the two are now up for grabs, with Florida leaning toward Romney, according to a widely-read poll average by website RealClearPolitics.
There, Romney won an endorsement from the Orlando Sentinel, whose editorial reflected a widely-held disappointment in Obama's handling of the economy.
"We have little confidence that Obama would be more successful managing the economy and the budget in the next four years," editors wrote.
"For that reason, though we endorsed him in 2008, we are recommending Romney."
Obama has come in for Republican criticism for failing to lay out just what he would do in the next four years to improve the struggling economy. Romney has a five-point plan, but Democrats contend he has been light on specifics.
On Monday night, both men will be in Florida, in Boca Raton for a televised debate focused on foreign affairs.
Going into the campaign, Obama was seen as strong on foreign policy, thanks to his withdrawal of US troops from Iraq and decision to order a mission that killed al-Qaeda kingpin Osama Bin Laden.
But Romney's camp has hammered the president on his handling of the Middle East, accusing him of neglecting ally Israel and of underestimating the threat of extremist passions unleashed by the Arab Spring revolts.
Obama will hunker down at the presidential retreat at Camp David for weekend debate preparation, while Romney will do the same in Florida.