As the 2012 Republican presidential race turns its attention to South Carolina and the state’s Jan. 21 primary, the question on the collective mind of the GOP establishment can be summed up in four letters: WWND?

That’s short for “What Will Newt Do” as in: Will the former House Speaker make good on his ominous threat to go “all out to win” against frontrunning former Massachusetts governor Mitt Romney in South Carolina or is this just the latest strategic swerve soon forgotten from Gingrich?

Republican presidential candidate, former Speaker of the House Newt Gingrich speaks at his party on primary night January 10, 2012 in Manchester, New Hampshire. (Photo by Allison Joyce/Getty Images)

On the one hand, he sent an email to supporters this morning with the subject line “Do you want to stop Mitt Romney or not?” and this call to action: “There’s no more time for talking about stopping Mitt Romney. We’re going to do it next week in South Carolina or he’s almost certain to be the Republican nominee, whether conservatives like us want it or not. It’s up to you, right now.”

On the other hand, Gingrich — at least so far today — has seemed to pull back on the hot rhetoric he had been using to describe Romney’s time at Bain Capital.

As Politico’s Jon Allen reported, Gingrich didn’t mention Romney or Bain by name at a stop in Rock Hill, S.C. today; “South Carolinians are either going to center in and pick one conservative, or by default we’re going to send a moderate on to the nomination,” Gingrich said.

The Republican establishment is watching closely — and doing what it can to make clear to Gingrich that savaging Romney isn’t the way to win the race or keep up the sizeable brand (aka Newt Inc.) he has built for himself over the past decade.

“If he persists in trying to launch Newt nukes, then there will be those who react firmly in cutting off diplomatic relations and impose sanctions: invitations not extended, speaking opportunities cut off, certain TV opportunities don’t appear, help in clearing up campaign debt isn’t offered,” said one senior Republican strategist closely monitoring Gingrich’s moves in the race.

The fear in Republican circles is that Gingrich may well be beyond the reach of the party establishment, having been set off by the attacks of a Romney affiliated super PAC against him Iowa. In short, it might be personal enough to Gingrich that reasoned conversations don’t work.

“If he had a chance of winning South Carolina I don’t think folks would begrudge him running attack ads on the front runner,” said one veteran Republican consultant of Gingrich’s tear down Romney threats. “But since it appears he doesn’t have any real chance of winning, it is pretty damning.”

If Gingrich does decide to push forward with his promised attacks — and his actions on the trail in South Carolina today suggest he may be rethinking that strategy — one Republican lobbyist said there may be only one course of action.

“Everyone that knows Newt, knows talking to him would be useless,” said the source. “But maybe people are trying to talk to [Sheldon] Adelson.”

Adelson is the Las Vegas casino magnate — best title ever? — who has pledged $5 million to Winning Our Future, a pro-Gingrich super PAC. The PAC has reserved $706,000 in ad time this week in the Palmetto State that begins today, according to buy information obtained by the Fix. (Restore Our Future, a Romney-aligned super PAC is slated to spend more than $1 million on ads in the state this week alone.)

The first South Carolina ad from Winning Our Future, which went on the airwaves in the state today, was a positive spot touting Gingrich’s conservative credentials.

Predicting what Gingrich will do next is a fool’s errand. (Make sure to read this terrific piece by the Post’s Amy Gardner on “nice Newt” and “nasty Newt”.) Remember that as recently as two weeks ago, he was promising to run an entirely positive campaign. He then switched to promises of hard-hitting contrasts with Romney and now may have backed off of that strategic gambit.

But what Gingrich ultimately does decide to do could well have an impact on how bruised Romney emerges from South Carolina — remember the bloodbath in 2000 between George W. Bush and John McCain — and how this campaign and the Republican party will remember and regard Gingrich.