Rep. Gabrielle Giffords (D-AZ), who was shot in the head during a 2011 assassination attempt, announced that she will resign from Congress this week in order to focus on her continuing recovery, the Arizona Republic reports.

“Giffords, whose ability to speak was damaged by the gunman’s attack, made the announcement herself in a YouTube video posted to her account. She plans to attend President Barack Obama’s State of the Union address on Tuesday and will resign sometime after that.”

Washington Post: “According to state law, Gov. Jan Brewer must set a date for a special election primary 80 to 90 days after Giffords formally steps down, and a general election will be set for 50 to 60 days after the primary. So the primary election for Giffords seat will likely be held in late April with the general election in June.”

John Heilemann: “If Gingrich wins Florida, the Republican Establishment is going to have a meltdown that makes Three Mile Island look like a marshmallow roast.”

“Why? Because the Establishment will be staring down the barrel of two utterly unpalatable choices. On the one hand, Gingrich’s national favorable-unfavorable ratings of 26.5 and 58.6 percent, respectively make him not just unelectable against Obama but also mean that he would likely be a ten-ton millstone around the necks of down-ballot Republican candidates across the country. And on the other, Romney has shown in two successive contests — one in a bellwether Republican state, the other in a key swing state — an inability to beat his deeply unpopular rival. If this scenario unfolds, the sound of GOP grandees whispering calls for a white knight… will be deafening.”

Mitt Romney has two advantages as the Florida primary approaches on January 31: money and early voting. Romney and an aligned Super PAC
have spent more than $7 million of airtime already in the state and nearly 200,000 Republicans have already cast their votes.

But Politico notes Newt Gingrich heads into Florida “emboldened by two assets that will test Romney’s organization and money there: the momentum from a double-digit victory and a conservative base that appears to be coalescing. But the results here revealed Romney’s weakness as much as they hinted at Gingrich’s potential. The establishment favorite didn’t just lose South Carolina – he got thrashed,”

First Read adds that the GOP electorate in Florida “has the potential to be unkind to Romney. Think South Carolina but with Cuban Americans in Miami thrown into the mix. According to the 2008 exit polls, 61% of Florida Republican primary voters considered themselves conservative (68% said they were conservative in South Carolina last night). And remember: Florida’s primary is closed, meaning that independents don’t get to vote. After all, it’s the same electorate that picked Rick Scott in 2010 over establishment favorite Bill McCollum.”

Adam Smith: “As important as money, television advertising and organization are here,
momentum tends to trump everything else in widely watched presidential
campaigns. Romney easily outspent and out-organized John McCain in
Florida in 2008 and still lost.”

“One or two more defeats and who knows what he’s going to say….I think he’s been dancing on eggs trying to find a version of Romney that will work.”

— Newt Gingrich, in an interview on Face the Nation, about GOP presidential rival Mitt Romney.

Mitt Romney told Fox News that he will release his tax returns for 2010 on Tuesday, with an estimate of his 2011 returns.

Said Romney: “We made a mistake holding off as long as we did.”

First Read: “Romney is not going to be the de-facto nominee until he wins over the conservative base of his party (outside of New Hampshire). And last night in South Carolina, that base overwhelmingly broke for Gingrich. Among voters who described themselves as “very conservative” (who made up 36% of last night’s primary electorate) Gingrich beat Romney, 48%-19%. Among Tea Party supporters, Gingrich had a 20-point edge, 45%-25%. And among those who are evangelicals or born-again Christians (who made up 65% of the electorate) Gingrich won, 44%-22%. And just as importantly, these folks finally coalesced around one anti-Romney alternative — and that person was Gingrich.”

“Ultimately, Romney’s problem right now is message — not mechanics. And as we saw in 2008, Romney doesn’t do the attack well. That’s what is going to make Monday night’s NBC debate so fascinating to watch.”

“It’s a real possibility. Right now I’d say it’s 50-50. The base wants its chance to have their say. They aren’t going to want it to end early, before they get their chance, which means that the process could go all the way to Tampa.”

— Former RNC Chairman Michael Steele, quoted by the Huffington Post, on the chances of an open or undecided Republican National Convention.

Former Florida Gov. Jeb Bush (R) told Bloomberg he will “stay neutral” in the state’s Republican presidential primary while warning his party’s candidates to leave the “circular firing squad” of their debates behind and start appealing to a broader audience.

James Carville: “Memo to Republican Establishment: Let me break it to you gently — you’ve got a first-class disaster on your hands. I know you boys thought this thing would work out and you would be able to whip the Republicans in line to fall in behind Mitt (I assume you are all males but if there is a female in the establishment, I apologize.) Not going too good, is it fellows?”

Andrew Sullivan: “This is the Republican crack-up people have been predicting for years. Gingrich is on a roll. I think he can win this – and then lose this in a way that could change America history. That is a brief impression in one moment of time. But I cannot see Romney winning this at this point. They are just not into him, and he’s an awful candidate.”

Brad Phillips: “If Mitt Romney had won, he would have become the de facto nominee earlier than any other presidential candidate in U.S. history, meaning that he alone would have had to endure more media scrutiny – for a longer period of time – than any of his predecessors. Instead, he’ll now continue to share the media’s harsh glare with Newt Gingrich, a severely flawed candidate who will steal some of the limelight and help buffer Mr. Romney’s coverage. More stories about Mr. Gingrich’s angry ex-wife and messy leadership as House Speaker means fewer stories about Mr. Romney’s tax returns and Bain Capital.”

Jonathan Chait: “My view all along has been that any remotely plausible candidate could beat Mitt Romney. My current view is that there are no remotely plausible candidates, which leaves us with Newt. So we have the immovable object meeting the irresistible force, except the exact opposite. Like almost everybody outside Gingrich’s immediate family, I had already written him off twice. But he really seems okay. If some really crazy rich conservatives decide to write him some seven- or eight-figure checks, who knows?”

Newt Gingrich overwhelmingly won the South Carolina Republican presidential primary, according to projections by most of the television networks.

By any measure, it’s a devastating loss to frontrunner Mitt Romney who once led in the polls by double digits hoped to finish off his rivals in the Palmetto State. If Gingrich can keep his momentum going into Florida’s primary at the end of the month — a big question — the GOP race could once again be up for grabs.

The winner of the 2012 Iowa caucuses was Rick Santorum, but the Des Moines Register reports, “the loser, it’s becoming clear, was Iowa.”

“The certified results released this week from the nation’s first presidential nominating contest revealed that Mitt Romney’s declared eight-vote victory on caucus night was actually a 34-vote defeat. They revealed that eight voting precincts went missing in action, and their votes will never be counted. And they were accompanied by evolving statements from the Republican Party of Iowa, which, having initially called the race for Romney, first declared this week’s result a ;split decision’ and only later acknowledged victory for Santorum.”

“Such a muddled result and response threatens the already-contested legitimacy of Iowa’s first-in-the-nation status and underscores the need for reforms to professionalize the voting process.”

“I think you’re going to see the same kind of long slog that you saw in
’76, with Ford and Reagan, that it took the whole
thing to win.”

— Former New Hampshire Gov. John Sununu (R), quoted by the Huffington Post, managing expectations for a possible Mitt Romney loss in South Carolina.

Mitt Romney says he will attend the next GOP presidential debates in Florida, the AP reports.

“After last weekend’s two debates in South Carolina, advisers to the former Massachusetts governor had said the candidate hadn’t committed to any more campaign debates. But Romney said Saturday, on the day when South Carolinians are voting in their state’s GOP primary, that he will be at the Tampa debate on Monday, and advisers say he also will participate in the Jacksonville debate on Thursday.”

Although Mitt Romney’s campaign is buzzing about new momentum in South Carolina, BuzzFeed finds that many of the students cheering on the candidate at a recent University of South Carolina rally were actually Brigham Young University students and young Mormons from Wasnhington, D.C. and Virginia “who traveled to the Palmetto State to give their
coreligionist’s presidential effort a much-needed jolt of energy.”

CNN reports the latest low point in the attacks on Newt Gingrich,
as it has discovered that a “fake CNN Breaking News alert was emailed to
state Republican activists early Thursday morning claiming that the
former House Speaker pressured his ex-wife to have an abortion.”

The
fake email reads: “A source close to Marianne Gingrich tells CNN that
former House Speaker Newt Gingrich forced her to abort a pregnancy
conceived during the affair that preceeded her marriage to Gingrich.”
Meanwhile,
ABC News notes that an equally deceiving fake press release followed
the email, meant to look as if it came from the Gingrich campaign. Key
fake quote from Gingrich: “I am not proud of some decisions I have made
or actions I have taken, but I believe in the power of redemption and I
trust the voters of South Carolina do as well.”

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.