Romney campaign opens fire on Santorum with first Michigan attack ad

Mitt Romney launched his first attack ad in Michigan, blasting Rick Santorum for supporting earmarks while "America is drowning in national debt."

The commercial comes as Romney is struggling to keep hold of his home state, where he grew up and where his father, George Romney, was a popular governor. Santorum has surged to a lead in recent polls, with an Inside MI Politics/MRG poll released earlier this week showing the former Pennsylvania senator with a 10-point lead over Romney.

The ad opens with video depicting a man drowning as on-screen text decries debt spending. The commercial then cuts to a clip of Santorum defending the earmarks he secured as a senator.

“I have had a lot of earmarks. In fact, I’m very proud of all the earmarks I’ve put in bills," Santorum says.

The ad then segues to Romney, who argues he would apply an economic litmus test to prevent unnecessary spending.

“The test that I’m going to apply: Is this program so critical that it makes sense to borrow money from China to pay for it?” the former governor of Massachusetts says.

Santorum himself went on air with a commercial critical of Romney earlier this week, that criticizes Romney for attacking fellow Republicans with negative campaigning.

"Mitt Romney's negative attack machine is back on full throttle," a narrator says as a Romney impersonator is shown trying to shoot mud at Santorum with a paintball gun. "This time Romney's firing his mud at Rick Santorum. Romney and his super-PAC have spent a staggering $20 million brutally attacking fellow Republicans. Why? Because Romney's trying to hide from his big-government RomneyCare, and his support for job-killing cap and trade."

The ad concludes with the Romney impersonator accidentally being sprayed with his own mud.

Romney was asked to respond to that ad during an appearance Wednesday on "Fox & Friends."

"That's the nature of politics, which is you always accuse the other guy of what you've done yourself. So my campaign hasn't run any negative ads against Rick Santorum," Romney said. He later foreshadowed today's release, saying that "doesn't mean we won't go after him."