Make it a good one. If the GOP is scared of anyone getting the nomination, it's Newt Gingrich. He'll challenge the status quo whereas Santorum will be run over by the establishment GOP in DC. IMO, Santorum is a weak version of Mike Huckabee.
The thing about Newt is that while they might be able to attack him personally, I don’t think that he drags down the rest of the ticket if he loses. Santorum, on the other hand, fills the leftist boogeyman role of religious extremist to a T, and they’ll use that to scare voters.