Earlier this week, the Rick Santorum campaign reminded potential voters that Newt Gingrich has made more than one “deal” with liberals. Today, his campaign released a new minute-long satellite radio ad that pinpoints the problem with Gingrich’s fanciful idea to build a moon base: We simply can’t afford it.

“Reckless spending has led to a 15 trillion dollar national debt … And what does Newt Gingrich suggest? Spending half a trillion dollar on a moon colony,” the ad says.

Gingrich received criticism from the comment he made last week in Florida, and Team Santorum uses it in the new spot to paint the former Pennsylvania senator as the true conservative in the 2012 race.

“Rick Santorum, he doesn’t just talk a good conservative game, he lives it,” the ad says.

The spot also features Gingrich saying, “When we have 13,000 Americans living on the moon, they can petition to become a state.” That kind of idea makes for great audio, but the ad’s broader point — that Santorum remains relentlessly focused on the debt — would be as true if the spot tackled the two candidates’ plans for entitlement reform rather than Gingrich’s more extreme moon proposal.

To listen to the audio of the ad, click here.