It’s tough, but it doesn’t feel tough, does it? This is Romney 101, stuff that every conservative who hasn’t been in a coma for the past two years already knows and dislikes about Mitt. But since there are in fact plenty of near-comatose (or, per the polite euphemism, “low-information”) voters, it might actually move the needle once it starts airing in SC. Consider it payback for the Romney Super PAC ads that have Santorum so worked up today.

Just one question: If this spot does end up hurting Romney, is Santorum the likely beneficiary? Over to you, Newt:

Despite having earlier suggested an loose alliance with his “junior partner” Rick Santorum, Newt Gingrich seemed eager to put further distance between himself and the former Pennsylvania senator in the lead-up to Monday’s GOP debate, warning conservatives that siding with Santorum was a vote for rival Mitt Romney.

“If you vote for Sen. Santorum, in effect, you’re functionally voting for Gov. Romney to be the nominee. The only way to stop Mitt Romney, for all practical purposes, is to vote for Newt Gingrich. It’s a fact. It’s a mathematical fact,” Gingrich said to reporters after an event in Myrtle Beach, according to the Wall Street Journal…

“Evangelical voters would like to have a nominee that will win a general election, and somebody who set the all time Pennsylvania record for the size of their defeat has a harder case to make as to why they could be elected,” Gingrich said.

I don’t know what he means by “mathematical fact.” True, Santorum has slid in South Carolina since his post-Iowa bounce and now trails Gingrich, but if Newt’s supporters defected to him en masse, he’d still have a fantastic shot at surprising Romney. What Newt really means to say, I think — and maybe he’ll say this bluntly tonight — is that Santorum’s still widely thought of as a boutique social-issues candidate whereas Gingrich is known for being a policy polymath. If you’re an independent thinking of rolling the dice on Obama’s opponent, who are you more likely to take a chance on: The guy who, according to the media caricature, is obsessed with abortion and gay marriage or the guy who’s known for being able to debate about nearly anything? This is going to be Gingrich’s message for the next week, I think, especially at the debates — that Romney can’t beat Obama and Santorum can’t beat Romney, therefore there’s only one truly, frankly, profoundly, fundamentally electable option still on the table. Turns out it’s the guy who finished fourth in both Iowa and New Hampshire. Who knew?

Says Mark Halperin, “Amazing to think about what would have happened if this ad had been run in Iowa for all of December with real money behind it.” Ah, but that would have required even a single semi-competent candidate besides Romney to be running this year.

Update: A good point from Bill Kristol about Newt’s supposed electability: It ain’t Rick Santorum whose favorables are nearly 30 points underwater.