The US presidential race grew increasingly hostile and bitter on Saturday with Barack Obama releasing an attack ad in which he denounced Republican rival Mitt Romney for shipping jobs abroad.
Obama, who with a stubborn unemployment rate of 8.2% is fighting historic precedent to keep his job, intensified his character assassination of Romney, pouring scorn on his opponent's business record.
The 32-second ad, titled "Firms," said Romney, when head of venture capital outfit Bain Capital, orchestrated moves that saw companies lay off workers in the United States in favor of opening up new plants in Mexico and China.
The commercial aired just days after the Obama campaign seized on government records that suggested Romney remained in charge at Bain for three years after 1999, when he contends that he stepped down.
Romney has described the Obama camp's claims about his alleged involvement at Bain in decisions where companies associated with the investment firm moved jobs abroad, as "false, misleading" and "wrong-headed."
The ad also accused Romney of outsourcing jobs to India while he was the governor of Massachusetts, the only public office he has held since giving up a lucrative business career in which he amassed a personal fortune.
And in a third salvo, the Obama-Biden campaign ad hit out at the Republican candidate for having "millions in a Swiss bank account," and of shoring up money in tax havens such as Bermuda and the Cayman Islands.
"Mitt Romney's not the solution. He's the problem," the ad concluded, building on several days of criticism leveled at the Republican challenger.
Romney on Friday reacted angrily to Obama's attacks on his time at Bain, where he amassed much of an estimated $250 million fortune.
But he also refused to bow to demands from the White House incumbent, a Democrat, to release more of his tax returns from past years.
The fierce exchanges signaled an escalation of an already heated campaign, in which Obama has sought to paint himself as a down to earth American -- in contrast to his portrayal as Romney as an "out of touch" destroyer of jobs.
But no US leader since World War II has won a second term while joblessness was above six%, other than Ronald Reagan, who won a second term despite unemployment being 7.2% in 1984.
Romney has played up his experience in the private sector, arguing that with the United States caught in a sluggish economic recovery, he is best equipped to deliver policies that can put more Americans back to work.
Democrats have rounded on his career at Bain, exemplified by a much used black and white photograph of Romney and fellow executives stuffing their pockets and mouths with dollars, to raise doubt over his motives for office.
Obama, currently on a tour of the battleground state of Virginia -- which he won in 2008 but could struggle to keep in November -- has been honing his attacks all week.
On Friday, the president said close scrutiny of Romney's career is justified because his opponent is using his business background and ability to become "Mr Fix-It on the economy," as "his main calling card," with American voters.
Romney responded by taking to the television studios in a bid to stem the damage.
"The president needs to take control of these people," Romney said on ABC News. "He ought to disavow it and rein in these people who are running out of control.
"He sure as heck ought to say that he's sorry for the kinds of attacks that are coming from his team," he added.
Romney's wealth has arisen frequently as an issue on the campaign trail but Obama's strategy to hone in on his opponent's record is considered risky as it may alienate voters who merely view the Republican as a successful businessman.
Romney has so far released only his 2010 tax returns and an estimate for 2011, despite Democratic pressure to release more information.
Obama won Virginia in 2008, a first for a Democratic White House candidate since Lyndon Johnson in 1964.
His tour through rural and urban Virginia follows visits to other key battlegrounds Ohio, Pennsylvania and Iowa. Obama is scheduled to continue his campaigning next week, traveling to Ohio, Texas and Florida over four days.