It’s a big day in South Carolina as Republicans head to the polls to make their pick for GOP nominee.

Can Mitt Romney win in a state where he finished fourth four years ago and essentially become the de facto nominee? Or will Newt Gingrich pull out a win after his candidacy was left for dead a second time?

Polls close at 7:00 pm ET.

A new Public Policy Polling survey finds Newt Gingrich heads into South Carolina primary day as the clear front runner in the state: he’s now leading with 37%, followed by Mitt Romney at 28%, Rick Santorum at 16% and Ron Paul at 14%.

Key finding: “Gingrich’s lead has actually increased in the wake of his ex-wife’s controversial interview with ABC. Although one night poll results should always be interpreted with caution, he led the final night of the field period by a 40-26 margin. One thing that continues to work to his advantage are the debates. 60% of primary voters report having watched the one last night, and Gingrich has a 46-23 lead with those folks.”

A new YouGov poll finds Gingrich at 33%, Romney at 29%, Paul at 18% and Santorum at 16%.

A new American Research Group poll shows Gingrich at 40%, Romney at 26%, Paul at 18% and Santorum at 13%.

“The idea that I am supposed to follow exactly what my dad did is not something I find terribly compelling.”

— Mitt Romney, quotes by The Hill, responding to those who note that
his father, former Michigan Gov. George Romney, started the tradition of politicians releasing their tax returns in
1967.

“To be in a neck-and-neck race at this last moment is kind of exciting. I
wish it were a winner-take-all-state. I wish we had all winner take all
states. But we don’t. So It looks like it’s going to be a longer
process than perhaps than that would have suggested.”

— Mitt Romney, quoted by the Miami Herald.

A new Clemson Palmetto poll in South Carolina shows Newt Gingrich leading the GOP primary race with 32%, followed by Mitt Romney at 26%, Ron Paul at 11% and Rick Santorum at 9%.

Twenty percent of the likely voters remain undecided.

Said pollster Dave Woodard: “We expect a reaction by the electorate to the personal revelations about Gingrich to be registered on Saturday, however, we do not think it will be substantial enough to erase the lead Gingrich has over Romney.”

Mitt Romney’s once 24 point lead in the Gallup daily tracking poll is now down to just 10 points. Gallup editor Frank Newport told MSNBC that Romney’s support was “clearly
collapsing.”

The poll is a five day rolling average so it doesn’t even fully reflect the last few days which, of course, haven’t been Romney’s best.

From the “oops” heard ’round the world to his allegedly drunk speech, the Daily Beast compiles some of Rick Perry’s biggest blunders on the presidential campaign trail.

A new Quinnipiac poll in Ohio shows Sen. Sherrod Brown (D-OH) crushing challenger Josh Mandel (R), 47% to 32%.

First Read points out Mitt Romney’s fundamental problem: “He’s been unable so far to win over conservatives in a conservative state. And if he’s unable to beat Gingrich and Rick Santorum in South Carolina — both of whom have their shortcomings — it would send a flashing warning signal to party leaders. What’s more, it would produce chatter, fair or not, that the party needs to find someone else, just as Indiana Gov. Mitch Daniels is set to deliver the GOP response to President Obama’s State of the Union on Tuesday night.”

“And chew on this: Did Team Romney make a mistake by playing so hard in South Carolina? As soon as his campaign gladly accepted Gov. Nikki Haley’s endorsement, it raised the stakes of a contest that was never going to be easy for him.”

Nate Silver: “I had written a post on Tuesday that challenged the
notion that there was a true ‘anybody but Romney’ constituency among
Republican voters… But now I’m wondering if that is the right
interpretation. Mr. Gingrich’s gain in the polls has occurred so rapidly
that few political writers have taken a step back to analyze it. What’s
interesting, however, is that in each of the first three voting states,
there is a different “not Romney” candidate who has surged late in the
race: Mr. Santorum in Iowa, Jon M. Huntsman Jr. in New Hampshire, and
now Mr. Gingrich in South Carolina… Where I think things become
potentially dangerous for Mr. Romney is when he plays into this tendency
by playing prevent defense, and behaving as though the nomination is
his to lose… Our forecasts now say that Mr. Gingrich has become the
slight favorite to win in South Carolina. We will see whether that comes
to fruition, but Mr. Romney’s prevent defense has allowed Mr. Gingrich
to drive to his 30-yard line.”

Mitt Romney said at last night’s debate “he’ll release his tax returns in April — but the booing that drew suggests Republican primary voters don’t appear willing to wait,” Politico reports.

“The tax returns delay provides the opening for growing suspicion and unease about the candidate who’s been leading the polls here.”

Jonathan Cohn: “What is in Mitt Romney’s tax returns? I have no idea, but I’m starting to wonder if it’s even more damning than speculation has suggested. Romney’s answers on the tax questions were rambling and unclear, which is remarkable for a candidate who is so intellectually sharp, who prides himself on careful preparation, and who had to know the question was coming. This issue has rattled him, obviously, and I’m eager to find out why.”

Dave Weigel: “The tax return question was totally predictable, and Mitt Romney blew it.”

Andrew Sullivan: “Romney then completely flounders in response to John King’s brilliant citation of George Romney’s position on the matter. And that word — ‘maybe’ — in answer to a direct and simple question is devastating.It not only makes him look shifty; it makes him look as if he doesn’t respect his own father’s honorable example.”

Walter Shapiro: “Thursday night’s four-top GOP debate made it official: The South Carolina primary has become a referendum on Newt Gingrich. Just 10 days after he was left in a dustbin labeled ‘Yesterday’s Man’ after dismal finishes in Iowa and New Hampshire, Gingrich has confounded the experts yet again. The oft-derided and consistently under-estimated House speaker has now bested Jesus in his sheer number of resurrections — an association that can only help as the South Carolina primary vote looms.”

A new We Ask America poll in South Carolina shows Newt Gingrich leading the GOP field with 32%, followed by Mitt Romney at 28%, Ron Paul at 13%, Rick Santorum at 9%, Rick Perry at 3% and Jon Huntsman at 3%.

A new  Public Policy Polling survey also show Gingrich continues to lead Romney, 35-29, with Paul and Santorum each tied for third at 15%.

Nate Silver: “Our forecasts now say
that Mr. Gingrich has become the slight favorite to win in South
Carolina.”

“No, but I will.”

— Newt Gingrich, when asked in last night’s Republican presidential debate whether he would like to respond to
reports that he requested an “open marriage” with his ex-wife. Those
words began a five minute attack on the media which Alex Roarty calls “one of the most memorable moments in debate history.”

Elizabeth Warren, the likely Democratic challenger to Sen. Scott Brown
(R-MA), raised over $1 million in just 24 hours during their first
“money bomb” of the election, The Hotline reports.

Not so fast:
“There aren’t many candidates who can muster that kind of support in a
money bomb. One of them, though, is Warren’s opponent: Almost exactly
two years ago, when Republicans started to think they had a real shot at
winning the seat, Sen. Scott Brown raised more than $1 million a day,
three days in a row.”

With Rick Perry now out of the race, the four candidates remaining on the stage tonight had a chance to really engage with one another at the last debate before the South Carolina presidential primary.

Newt Gingrich won the night on the first question, when he trained his fire on the media and debate moderator John King for focusing on claims by his ex-wife that Gingrich had requested an “open marriage.” He denied the allegations and received multiple standing ovations during the exchange. No other moment from the night was nearly as memorable. The rest of Gingrich’s night came in around par, but those first moments may be all he needed to capture the headlines and continue his recent momentum.

Rick Santorum also did well, landing a number of substantive punches on Mitt Romney for his Massachusetts health care program, as well as on Gingrich for his tenure as Speaker of the House. Santorum’s campaign has clearly done an effective job on their opposition research. He also gave some of the most detailed answers on policy questions and did his best to create some space between his positions and those of his opponents.

Romney once again had an average performance and stumbled when asked about releasing his federal income tax returns, which he finally committed to releasing in April. After two less-than-stellar debates in a row, it’s unclear whether he can hold on to his narrowing lead in South Carolina.

Ron Paul had great difficulty getting time in the debate and the other three candidates generally declined to engage him. At times his responses seemed to ramble.