ABC News' Shushannah Walshe and Michael Falcone Report:
DETROIT - Ahead of Tuesday's primary Rick Santorum's campaign has released a new negative ad attacking Mitt Romney which specifically targets Michigan voters.
The commercial, which has already begun hitting television airwaves, hits Romney in his home state for supporting "Wall Street bailouts while turning his back on Michigan workers."
Over images of workers in hard hats, the narrator says, "Who's on the side of Michigan workers? Not Romney. He supported the Wall Street bailouts while turning his back on Michigan workers, but Rick Santorum's 'Made in the U.S.A.' plan changes everything. It cuts taxes for Michigan manufacturers to zero, so we can bring American jobs back from overseas."
Though the ad criticizes Romney for "turning his back" on Michigan auto workers, like the former Massachusetts governor, Santorum did not support the federal bailouts of General Motors and Chrysler. That fact is omitted in the ad, and Santorum does mention it on the campaign trail - even in Michigan.
It's a stance that Romney has struggled with because of his nuanced position on the bailout (he supported a managed bankruptcy for the automobile companies) as well as the success the car makers have had since the bailout.
Both candidates have said while campaigning in the state that they believe the companies would be as successful as they are now without government assistance. The second half of the 30-second spot focuses on Santorum's "Made in America" jobs plan, one of his only television ads to focus solely on the economy and not social issues.
The narrator says that Santorum's plan "cuts income taxes for all workers." Romney's plan - which he released on Wednesday - does that as well cutting all six current tax brackets by 20 percent.
"Rick Santorum: he's fighting for us," the ad concludes, pushing a populist message.
Romney campaign spokewsoman Andrea Saul labeled the ad a "desperate" and "false" attack.
"Congressman turned Senator Santorum is the epitome of what's wrong with Washington: he admitted he 'takes one for the team' rather than standing up for principles," she said in a statement. "He voted to raise the debt ceiling without accompanying cuts, to give felons voting rights, to raise his own pay and for liberal judge Sonia Sotomayor."