Undeterred by independent fact checkers that have debunked the thrust of their claims, the Obama campaign is redoubling attacks on Mitt Romney as an "outsourcer" in a new TV ad airing in eight battleground states.

The 30-second spot - titled "The Problem" - claims Romney condoned the Chinese "taking our jobs and taking a lot of our future."

"He made a fortune letting it happen," the narrator says, focusing on Bain Capital outsourcing to China, a country Romney has vowed to challenge as president.

It's the latest in a steady drumbeat of negative attacks on Romney's record as a corporate buyout specialist, alleging he profited off of deliberately bankrupting companies and sending jobs overseas.

The inclusion of China in the new ad also comes as Obama tries to bolster his image as a hard-liner against China. On Thursday, the administration lodged a new complaint against China at the World Trade Organization, challenging tariffs on U.S. auto exports. The case coincided with Obama's campaign bus tour through auto manufacturing country of Ohio and Pennsylvania.

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The Romney campaign called the latest ad a continuation of "desperate lies," citing reports by several independent fact-checkers that have discredited the suggestion that Romney himself had a direct role in relocating U.S. jobs overseas.

"We found no evidence to support the claim that Romney - while he was still running Bain Capital - shipped American jobs overseas," FactCheck.org concluded in a report last month.

Washington Post fact checker Glenn Kessler also concluded that while Bain-owned companies may have engaged in outsourcing, Romney's ties to the practice are tenuous.

The ad blitz comes in spite of Obama's comments to audiences on his bus tour last week decrying the negative tone of the campaign on TV.

"You guys are getting bombarded with all kinds of nonsense on TV. So I know that sometimes politics can be discouraging, and especially Washington politics can be discouraging, and it can seem small and it can seem petty," Obama said Friday.

Independent media monitors that track campaign advertising report that 76 percent of the TV ads Obama's campaign has aired over the past month have had a negative, "anti-Romney" message.

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