Romney and his Republican running mate Paul Ryan meanwhile struggled to explain the accounting in their taxation plans, with fiscal policy and slow job creation taking centre stage in the White House race.
In Florida, Obama courted retirees by lambasting Romney’s plans to reform the Medicare health care system for the elderly.
He also picked apart interviews in which the two Republicans declined to name any of the tax loopholes they plan to close to make their promise to cut taxes, while also trimming the deficit, add up.
“I guess my opponent has a plan but there is one thing missing from it – arithmetic!” Obama said.
“It was like two plus one equals five. They couldn’t answer questions about how they’d pay for US$5 trillion in new tax cuts and US$2 trillion in new defence spending without raising taxes on the middle class.
“That’s not bold leadership – that’s bad math. That gets a failing grade,” said Obama, who had warned in an earlier interview with CBS News that the rich would have to pay more in taxes to alleviate the burden of the middle class.
In television appearances, Romney and Ryan declined to specify how exactly they would cut loopholes in the tax code to pay for rate reductions.
The Republican nominee, a multi-millionaire, also denied he planned to cut taxes for the rich.
“I want to make sure people understand, despite what the Democrats said at their convention, I am not reducing taxes on high-income taxpayers,” Romney said on NBC’s “Meet the Press.”
As his armored bus trundled from west to east through Florida, Obama plunged into restaurants, diners and bars.
At one stop, he was surprised to be lifted a foot off the ground by hulking and exuberant pizza shop owner Scott Van Duzer.
“Look at that!” the president said once 113 kilograms, 1.90 meters Van Duzer had deposited him back on terra firma.
“Man, are you a power lifter or what?”
Florida is a perennial swing state and has the most electoral votes – 29 – of all the most contested battlegrounds in the election. Recent polls have shown the president with a narrow lead over Romney.
Large weekend crowds that greeted the president have aides optimistic that Obama can repeat his 2008 victory here. Should he win Florida, the president would severely undermine Romney’s hopes of snatching the White House.
“We’ll do pretty well in the corridor,” a senior Obama aide said, referring to the contested territory along Interstate 4 where Florida elections are won and lost.
“It’s going to be close.”
Retirees, many fleeing cold northern winters, form an important part of the state’s electorate, hence Obama’s Medicare attack.
The Republican’s plan to convert Medicare to a voucher system over time would end up with patients paying higher out-of-pocket costs, the president charged.
“I want you to know, Florida, I will never turn Medicare into a voucher,” Obama said.
The president’s trip, however, was marred by a tragedy when a Florida police officer escorting President Barack Obama’s motorcade died Sunday after he was struck by a vehicle.
Meanwhile, Romney intensified his attack on Obama’s stewardship of the economy, two days after the latest Labor Department data showed only 96,000 jobs were generated by the economy last month.
“It’s a jobless recovery, if it’s a recovery at all,” Romney said.
“You’re not seeing the kind of job growth that keeps up with population growth. You’re not seeing any wage growth. It’s not at all what a recovery is supposed to look like,” Romney said on “Meet the Press.”
The former Massachusetts governor also had a crack at Obama on Iran, saying the president’s “biggest failure” was not halting the Islamic Republic’s nuclear ambitions.
Several daily tracking polls detected a increase in Obama’s small polling lead following the Democratic National Convention in North Carolina.
Obama led Romney by 49 to 44 percent in Gallup’s latest daily tracking poll. His approval rating as measured by the same firm was 50 percent, down two points from a yearly high on Saturday.