Obama's re-election campaign, meanwhile, accused Romney of "not telling the truth."
"The truth is that the president is giving states additional flexibility only if they move more people from welfare to work - not fewer," Obama campaign spokeswoman Lis Smith said in a statement. " ... By falsely attacking a policy that both he and his Republican allies have supported for years, Romney is once again flip-flopping on a position he took in Massachusetts, and demonstrating that he lacks the core strength and principles the nation needs in a president."
Romney campaign Policy Director Lanhee Chen insisted that Romney has remained consistent in supporting work requirements for welfare recipients. Chen's statement said that as Massachusetts governor, "Romney vetoed efforts to weaken work requirements and he pressed repeatedly to instead strengthen them and bring them in line with federal standards."
Also Tuesday, a super-PAC supportive of Obama released a new ad tying Romney to the death of a former GST Steel worker's wife after her husband lost his job when the plant closed down.
Romney's former private equity firm, Bain Capital, acquired GST Steel in 1993, but the company went bankrupt in 2001, two years after Romney ceased day-to-day oversight of Bain.
The ad by Priorities USA Action features Joe Soptic, a former worker at the Kansas City-based steel plant, as he tells the story of how he lost health insurance benefits when the plant shuttered. He then says his wife passed away from cancer after that. Soptic's wife died in 2006.
"I do not think Mitt Romney realizes what he's done to anyone, and furthermore I do not think Mitt Romney is concerned," Soptic says.
Romney's campaign issued a harsh reaction.
"President Obama's allies continue to use discredited and dishonest attacks in a contemptible effort to conceal the administration's deplorable economic record," Romney spokeswoman Amanda Henneberg said in a statement.
Expect more of the same. Last week, CNN reported that Priorities USA Action has reserved $30 million this fall for broadcast and cable time. And on Tuesday, a major fiscal conservative group that has spent tens of millions of dollars on ads critical of Obama revealed it will spend at least $7 million for new spots starting Wednesday in 11 battleground states: Colorado, Florida, Iowa, Minnesota, Nevada, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia, and Wisconsin.
Americans for Prosperity, which is partially funded by the influential Charles and David Koch, said it will rotate different ads and messages over the next three weeks in the campaign that could cost as much as $27 million.
The billionaire Koch brothers are high-profile figures in the Republican Party who support conservative and libertarian causes. Backers of Americans for Prosperity, the pair of industrialists are expected to spend tens -- if not hundreds -- of millions on Republican causes this year.