President Barack Obama's camp took aim at Mitt Romney's governorship of Massachusetts, saying his "disastrous" tenure resulted in fewer jobs and more debt but left the wealthy better off.
The offensive came as a report suggested that Romney's allies in big business could pour $1 billion into the campaign to beat Obama and his Democrats in November, leaving the president at a steep financial disadvantage.
Obama's political advisor David Axelrod dissected Romney's record in Massachusetts between 2003 and 2007 in a campaign memo, five months before an election polls suggest will be tight and won in a few key states.
It was the latest effort by the president's team to negatively define Romney's past record for voters and to focus November's vote on the character of the challenger and not Obama's own vulnerabilities on the economy.
The assault follows Obama's bid to puncture Romney's claim that his business experience fits him to turn around the US economy, by focusing on a previous career as a venture capitalist which made him a multi-millionaire.
"Mitt Romney applied the economic philosophy he learned in the private sector to disastrous results as governor of Massachusetts," Axelrod wrote.
"Now he's making the same promises he made when he was running for governor. We've seen this all before.
"It's the same formula that benefited a few, but crashed our economy in the first place and undermined security for the middle class. Massachusetts couldn't afford Romney Economics, and neither can the American economy."
Romney has not dwelt much on governorship, apparently because Massachusetts is a liberal state reviled by conservatives who select the Republican nominee.
He is also known for a health care reform which was used as the model for Obama's signature medical insurance overhaul which Republicans have pledged to overturn.
Axelrod said that under Romney, Massachusetts plunged from 36th to 47th out of 50 states in job creation, and despite promises to the contrary raised taxes and fees on middle class families and small businesses.
"Meanwhile, he cut taxes for millionaires like himself, handing over more than $75 million to just 278 of the wealthiest in Massachusetts," Axelrod wrote.
The latest sparring came a day after Romney formally captured the Republican nomination by passing the needed threshold of 1,144 convention delegates.
Obama marked the occasion by calling Romney to congratulate him for his victory and pledged a "healthy debate" about America's future, spokesman Ben LaBolt said.
Romney's camp said the call, which had the potential to be frosty as neither man appears to like the other, was "brief and cordial."
The brief moment of civility did not last long.
Romney's Boston-based team took aim at Obama's job creation record, days ahead of the latest politically sensitive Labor Department employment data, which will be watched for any sign that a slowing economy is gathering steam.
Obama had repeatedly demonstrated "hostility to job creators," said Romney campaign spokeswoman Andrea Saul, singling out Obama's top legislative achievements health reform and a financial regulatory overhaul.
"These misguided policies have prevented businesses from growing and creating new jobs. As president, Mitt Romney will work from day one to repeal these disastrous laws and allow businesses to begin hiring again."
The strength of Romney's challenge was meanwhile underlined by a report on the Politico website which said Republican fundraising committees largely funded by conservative corporate titans would spend $1 billion on the election.
The groups, allowed to dish up unlimited sums by a landmark Supreme Court ruling, will blitz battleground states with savage TV, radio and Internet ads battering Obama's candidacy and those of congressional Democrats.
Corresponding Democratic Super PAC committees have struggled to raise money, and the Politico report raised the likelihood that Obama will be seriously outspent as he asks voters for a second term amid tough economic conditions.
Romney meanwhile got to work polishing his image, as polls show he is viewed as less likable than Obama.
One sugary spot related the day his wife Ann was diagnosed with multiple sclerosis.
"As long as it's not something fatal, I'm just fine. I'm happy in life as long as I've got my soul mate with me," Romney said in the video.
In the other ad, Romney promised to restore what he sees as the "promise" of America on election day November 6.
"The dreamers can dream a little bigger, the help wanted signs can be dusted off, and we can start again. And this time we'll get it right," he said.© ANP/AFP