Today’s New Hampshire primary has been Mitt Romney’s sure thing for a long, long time. And have no doubt — he’ll win this thing. But the Romney that walks out of New Hampshire will be badly bruised, and headed for even more of a beating in South Carolina.

Here’s the thing: Romney decided to play dirty in Iowa with Newt Gingrich and now he’s getting his comeuppance. And because the GOP establishment decided early on that not only was Romney the nominee but that there were questions about Gingrich, Newt’s assault is of the no-holds barred, scorched earth variety. Gingrich knows he has absolutely nothing to lose.

Gingrich, as everyone knows, was leading the polls in Iowa in early December until a trio of rivals — Romney, Ron Paul and Rick Perry — ganged up on him with a barrage of negative ads that destroyed his campaign.

But what seems to be sticking in Gingrich’s craw is the way Romney did it. While Paul and Perry put their names behind “paid for by” labels at the end of their commercials, in an attempt to keep his hands clean, Romney hid behind a superPAC called Restore Our Future.

And then he claimed he had nothing to do with it, couldn’t control the ads and suggested Gingrich get out if he couldn’t take the heat. (Seriously, has he met Gingrich?  Cuz that’s red meat to ol’ Newt.)

Even at the debates this weekend, Romney tried to pretend he hadn’t even seen the ads, but then flubbed it and referred to the “the ad I saw.”

And now Gingrich has taken the gloves off, no longer even pretending he’s running a positive campaign. By South Carolina I suspect he’ll stop pretending he’s running a presidential campaign and just make it a Kill-Mitt’s-Dream campaign.

At Sunday’s debate, Romney got hit quite a few times, as might have been expected. Rick Santorum needled him about not running for re-election in Massachusetts. Jon Huntsman got a nice punch in defending himself for serving as ambassador under President Obama, making Romney look like some partisan hack.

But it was Gingrich who killed: “Can we drop a little bit of the pious baloney?” he asked after Romney tried to pretend that he’s a reluctant politician. Gingrich then ran through Romney’s failed attempts at election during the last 20 years.

Did that hurt? Well, Romney has gone from 40+ percentage in the polls to about ten less in the last week, particularly since the weekend. If the New Hampshire primary was next week, I’m not sure he’d prevail.

Keep in mind that he’s lost those 10 points with Gingrich and Paul barely moving in the polls. And after an initial post-Iowa spike, neither has Santorum. Perry’s not even trying in New Hampshire, having already started the anti-Romney bandwagon in South Carolina. (The beneficiary seems to be Huntsman, whose first, second or third placing will ultimately be pretty meaningless because he has nowhere to go in South Carolina and will have to focus on Florida a week later, where he won’t do great anyway.)

In other words, Romney’s sinking because the doubts about him are staring to stick, not because a new leader or frontrunner has emerged.

He will still win New Hampshire — and by at least 20 points. And Paul will keep on rocking. Huntsman will do well. Gingrich will come in fifth and Perry last. The only one who can make something of a third or better showing, regardless of percentages, will be Santorum. (If he does that well, Santorum will have enough money to really compete in both South Carolina and Florida.)

But come South Carolina, Gingrich is going to make Romney’s life a living hell. His campaign is about to release a 27 minute ad that details the effect of Bain Capital’s “creative destruction” model of profiting.

Remember, for Gingrich, it’s not about winning the nomination anymore. You just never, ever, count out the Newt.