Amid signs that attacks on Mitt Romney's business record are resonating in several swing states, President Obama's re-election campaign is doubling down with a new TV ad that hits Romney as an "outsourcer" while promoting Obama as an "insourcer."

The 30-second spot, titled "Believe," attempts to draw a contrast between the two candidates on their tax policies.

Romney "supports tax breaks for companies that ship jobs overseas," the narrator says. Obama "favors tax cuts for companies that bring jobs home."

"Outsourcing verses insourcing. It matters," the spot concludes.

The Romney campaign called the ad misleading, noting that several independent fact-checkers have concluded that Romney did not have a direct role in shipping U.S. work abroad during his tenure at Bain Capital.

"Spending millions of dollars on untrue ads won't change the fact that President Obama's policies have left more than 23 million Americans struggling for work," Romney campaign spokeswoman Amanda Henneberg said.

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Still, the Obama campaign shows no signs of letting up on the outsourcing offensive. Aides say the new spot reflects a new phase in Obama TV advertising that will begin focusing on the candidates' contrasting visions for the future, rather than each individual's record independently.

"I do think these summer months are important months. We're going to be debating the difference between our vision and his vision," a senior Obama campaign strategist, speaking on condition of anonymity, told reporters last month.

"We're finishing the foundational phase from our standpoint of the last three and a half years and the Romney record, then I think we're going to have a debate about where we are now, what his ideas and vision are, what the president's ideas and vision are and we're going to drive that very hard," the strategist said.

The ad begins airing today in Colorado, Florida, Iowa, North Carolina, New Hampshire, Nevada, Ohio, Pennsylvania and Virginia, the campaign said.