Mitt Romney Ad: Rick Santorum's Economic Plan 'The Worst Idea Of Any GOP Candidate'

Mitt Romney goes after Rick Santorum for his economic credentials in an ad released Thursday by the campaign.

"Who can turn around the economy and beat Barack Obama?" the commercial's narrator asks over ominous music and interspersed images of Santorum and Obama. "Not Rick Santorum. Santorum's real weakness is the economy. He's never run a business or a state. His plan: economic illiteracy. Inexcusable. The worst idea of any GOP candidate. Rick Santorum: another economic lightweight."

The ad quotes negative assessments of Santorum's economic strategies, including a MarketWatch.com evaluation that says Santorum's "real weakness is the economy," and an article from The Hill that quotes Will McBride of the right-leaning Tax Foundation calling Santorum's plan "the worst idea" of any GOP candidate.

Romney's campaign has zeroed in on fiscal issues as a potential weakness for Santorum, who's perceived as being more in step with the right on social issues.

In an interview with Fox Business Network on Monday, Romney said Santorum was to his left on the economy, prompting Santorum to practically accuse him of being a socialist.