Rick Santorum now has an air strike in Minnesota in advance of the state's Feb. 7 caucuses.

The Santorum-supporting Red, White and Blue Fund, which also aired ads in Iowa and South Carolina, is spending over $100,000 to air the ads in the state. The ad goes after Santorum's opponents, claiming that President Barack Obama, Newt Gingrich and Mitt Romney are "not so different."

"Who can we trust? Rick Santorum. He's the only proven conservative with a bold plan to restore America's greatness," the ad says.

Santorum himself, who visited Minnesota on Monday, plans to return to the state Sunday and Monday, according to his campaign.

He will have company. Ron Paul, who began running ads in Minnesota last month, plans to visit again Saturday and Monday and there is word that Mitt Romney, who was in Eagan on Wednesday, may return to the state before next Tuesday as well. Newt Gingrich has not announced a Minnesota visit but may yet.

The Feb. 7 contest includes a non-binding straw poll that could give any of the candidates momentum as they battle it out.

Update:

The Romney-supporting super PAC, Restore Our Future, is also running ads in Minnesota.