Santorum turns tough rhetoric against Gingrich

His rivals often decry Newt Gingrich's scotched-earth rhetoric, but they are increasingly getting into the act themselves. Witness the newest broadcast ad from Republican presidential candidate Rick Santorum, which calls Gingrich's economic proposals "fiscal insanity."

The ad's wording and tone also borrows a read-between-the-lines theme that front-runner Mitt Romney has been using against Gingrich - that he is mentally unstable and therefore unfit for the presidency. In addition to liberal use of the word "insanity," a digital press release accompanying the ad makes note of "Gingrich's erratic behavior" and "wild ideas."

The text of the radio ad, which the Santorum campaign says will be aired nationally beginning Friday, says, "Reckless spending has led to a 15-trillion-dollar national debt. That's $50,000 of debt for every person in America, and it's crushing our economy. And what's Newt Gingrich suggest? Spending half a trillion dollars on a moon colony."

Gingrich's voice is heard describing his plan for permanent base on the moon by his second term as president, followed by the voice over saying, "Gingrich's idea is fiscal insanity. And another reason true conservatives are uniting behind Rick Santorum."

Actual government estimates of a lunar outpost range from $104 billion to $230 billion.

Santorum is hoping to consolidate the support of social conservatives and tea party voters behind his candidacy in Saturday's Nevada caucus and other upcoming primaries. That constituency was dominated by Gingrich in both South Carolina and Florida in primaries held last month.