Santorum ad attacks Gingrich's moon proposal

Rick Santorum has a new radio ad attacking Newt Gingrich on his proposal to establish a U.S. base on the moon.

According to the Santorum campaign, the ad is set to air nationally.

"Reckless spending has led to $15 trillion of national debt," the voice-over in the ad says. "And what does Newt Gingrich suggest? Spending half a trillion dollars on a moon colony."

The ad goes on to quote Gingrich saying that, if elected, by the end of his second term in office, the United States would "have the first permanent base on the moon."

"Gingrich's example is fiscal insanity," the ad continues.

The ad goes on to argue that Santorum is the most authentic conservative in the GOP presidential field. Santorum has focused his attacks on Gingrich recently in an effort to win over conservative Republicans who favor the former Speaker. Santorum and Gingrich are fighting to be the conservative alternative to front-runner Mitt Romney.

While campaigning in Florida before its primary on Jan. 31, Gingrich proposed putting a base on the moon. His suggestion was widely criticized by his opponents.