FAIRFAX, Virginia: US President Barack Obama and his Republican rival, Mitt Romney, on Saturday began preparing for their final debate, with Obama hunkering down at Camp David and Romney staying in Florida.

The third and last of their debates is scheduled for Monday (Tuesday in Manila) at Lynn University in Boca Raton, Florida.

On Friday, Obama set an aggressive tone accusing Romney of suffering from policy “Romnesia,” a barb dismissed by the Republican as pettiness 18 days before the election.

One night earlier, both men had traded light-hearted banter at a charity dinner, but on Friday the verbal attacks turned nasty, with the Democratic incumbent taunting Romney’s efforts to tack to the center 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 Robin-Hood-in-reverse 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 of three head-to-head debates set on Monday, the campaign returned to its tried and tested formula of branding Romney an untrustworthy flip-flopper.

The Republican nominee meanwhile campaigned in the biggest political battleground of all, Florida, where Monday’s debate will be held, and he didn’t hesitate to strike back at the president’s comments.

“They’ve been reduced to petty attacks and silly word games,” Romney told a crowd of more than 8,500 people at Daytona Beach, adding that Obama’s re-election bid “has become the incredible shrinking campaign.”

Romney, accompanied by his running mate Paul Ryan, laid into the incumbent for failing to map out his plan for another four years should he win re-election.

While Obama was addressing crowds in Virginia, a state he won narrowly in 2008 but where Romney is making up ground, his Vice President Joe Biden flew to Florida, where three of the race’s four main figures were stumping for votes.

On Monday night, Obama and Romney will be in the Sunshine State, 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.