Let's wrap this up for the night with a summary of the highlights, or what passed for highlights:
• Newt Gingrich gave a fiesty, popular performance, winning rounds of applause with combative answers on foreign and social policy, in his best debate performance in recent weeks
• Mitt Romney fended off criticism of his record and performance as a venture capitalist but got mired in attacks on negative advertising from Super Pacs supporting his candidacy
• Romney remained largely unruffled and as a result remains the strong front-runner in the coming primaries in South Carolina and Florida that will likely decide the 2012 Republican nomination
• Ron Paul stuck to his position on ending US military involvements overseas and defended his objections to the US assassination of Osama bin Laden, to audible booing from the debate audience
• Asked when he would release his tax records, Mitt Romney hedged, suggesting he would probably release them in April if he had won the nomination by then
• Newt Gingrich robustly defended earlier remarks about needing to instill "work ethic" into children from poor households by having them work part-time as school janitors and claiming that "only the elites despise earning money"
So where does this leave us? Both Santorum and Gingrich had pretty good debates overall but once again, bickering about Super Pac ads is not really a winning strategy.
It seems bizarre that in a debate like this, none of Mitt Romney's opponents have pressed the electoral liabilities that Romneycare brings with it, rather than banging on about his record with Bain Capital, which is weaker rod to beat him with in a GOP debate.
Romney had some points of weakness, getting embroiled in a tangle with Santorum on a detail that arose from a Super Pac ad. Then there was some more shiftiness over whether he'll release his tax returns – and Romney got away with a non-answer that basically said he'd think about doing it if he was the nominee.
But none of those things amount to much, even Romney's studied ignorance of what the Romney-supporting Super Pac's ads are saying – although he did stumble at one point referring to that as "my Super Pac". Romney's like a football manager who somehow doesn't see the foul by his own players yet has a photographic memory of fouls committed against his own side.
But nothing here will have changed the dynamic of the primaries at this point: Romney in the lead and his opponents splitting the anti-Romney vote between them.
Hey Frank Luntz has got a new wig. It looks good.
Is it possible to have too many debates? It feels like each of their candidates has been asked the same questions over and over again.
Bret Baier, the Fox News moderator, mentions that this was his fifth debate. Bret, that's nothing.
There are loud bangs in the background – probably fireworks going off, the Fox News talking heads say, nervously.
And with a whimper rather than a bang, that's it.
What is it with these debates tapering off at the end? Ennui?
Oh, Fox News has a Twitter gadget showing if viewers liked or disliked candidate's answers. Looks like everyone thinks Mitt Romney is an evasive charlatan. This probably makes him a more attractive candidate.
Romney has his own moans about Super Pac ads, saying of the Gingrich-supporting Super Pac documentary on Romney and Bain: "It's probably the biggest hoax since Big Foot."
Big Foot? Couldn't we have more up-to-date hoaxes please? It just feels a bit 70s.
Zing! Gingrich raps Romney over the knuckles again over the nasty Super Pac ads, saying acidly:
Mitt can't influence his Super Pac, makes you wonder how much influence he will have if he is president.
Guns and Mitt Romney! Romney signed an assault gun ban while governor of Massachusetts.
But Massachusetts doesn't count, as Romney points out, and also claims that everyone in Massachusetts was totally cool with banning guns, even the pro-gun people (but not the NRA).
That's what an upside-down state Massachusetts is: even the pro-gun people want to ban guns! So Mitt Romney was actually incredibly right wing, seasonally adjusted for Massachusetts.
But the fun part is when Romney is asked how much hunting he's done lately. Ever the prepared candidate, Romney says he went elk hunting and pheasant hunting at some unspecified time since 2007, looks uncomfortable and with mock-modesty concedes that he's not as big a hunter as "some others on this stage," such as Rick Perry.
Of course he finishes off this issue with a paradigmatic Romney quote:
I guess I enjoy the sport, and when I get invited I'm delighted to be able to go hunting.
If that answer was a cartoon it would be the one about the Curate's egg.
Yes, this is running through the laundry list of what the candidates want to bang on about. It's very dull.
Santorum and Gingrich are having some fracticidal in-fighting about how to reform social security. Gingrich manages to sound like an arse, repeating several times that he "balanced the budget" four years in a row, which isn't anywhere as true as he makes it sound.
Santorum's main point – that Gingrich's nutty plan for social security would blow out the deficit – is sound.
This debate is unraveling, as the questions seem to be aimed at candidates pet schemes or quirks.
For example.
For the multiple-ith time tonight, Mitt Romney quibbles with the moderators about how long he can speak for. It makes him sound whiny.
OK, a question for Rick Perry on the treatment of women in Turkey, among other things? This should be fun.
Did Perry just call Turkey's government essentially "Islamic terrorists"?
"There should be no space between the United States and Israel, period," says Perry. So he plans to abolish the Atlantic ocean?
RICK PERRY JOKE ALERT!
So... the moderators said there was no sound tonight to signal that candidates had run out of time but warned that they may bring one back if candidates keep going over time.
Rick Perry is asked if he wanted to say something during Ron Paul's "give peace a chance" answer just now. "I thought the sound you were looking for is a gong," snipes Perry.
I guess you had to be there. Or here. Or somewhere.
"We should not negotiate with the Taliban, we should defeat the Taliban," concludes Romney on this particular gig, yet another non-committment that you know a Romney White House wouldn't actually give the time of day to once in office.
Ron Paul's insane views that America can't just bomb anyone, anywhere comes under the spotlight.
"This whole idea that you can't capture anyone, why didn't we try to get some information from him?" wonders Ron Paul of Osama bin Laden, who thinks the US acted against international law (and this from someone who thinks the UN should be disbanded, so uh).
Lots of audience reaction while Ron Paul was speaking, including some shouting.
Newt Gingrich is offered the free "beat up Ron Paul on foreign policy and win prizes" response.
Ron Paul continues on his "no more war" theme, and again there are shouts and boos from the hall. Easily the nastiest response in any of the Republican debates so far.
Romney's response is that the American army should be so awesome that no one even thinks about messing with America. Yes that always works.
A rare photograph of Newt Gingrich (right) speaking in pubic. Photograph: Jason Reed/Reuters
A lively back and forth between moderator Juan Williams and Newt Gingrich over Gingrich's kooky stuff about making poor black kids work as janitors in schools. Williams points out that what's really offensive about that is Gingrich's claims about the need to instill work ethic, as well as his cheap shot about Barack Obama being a "food stamp" president. "It sounds like you are seeking to belittle people," says Williams.
This all goes down like a cup of cold sick – a phrase I recently used live on Australian Broadcasting Corporation news – with the audience, who loudly boo Williams. So it's come to this: booing the moderator? A Fox News moderator?
"I am quite sure Martin Luther King would be in agreement with me on this," says Ron Paul, after agreeing that the US judicial system was still rife with institutional racism.
Now that's something you don't hear often in a Republican debate.
Oh, Juan Williams of Fox News sneaks in a mention that Mitt Romney's grandfather was from Mexico – and gets some boos from the audience.
This is the opportunity for Romney's vast anti-immigration pander. None of which would actually be carried out by a Romney White House, but never mind. It's not like he's running to be governor of Massachusetts, right?
Here's the transcript of Romney's non-promise to release his tax returns, complete with "time will tell" hedging:
Moderator: Governor, will you release your income tax records?
Romney: You know, I looked at what has been done in campaigns in the past with Senator McCain and President George W Bush and others. They have tended to release tax records in April or tax season. I hadn't planned on releasing tax records because the law requires us to release all of our assets, all the things we own. That I have already released. It's a pretty full disclosure. But, you know, if that's been the tradition and I'm not opposed to doing that, time will tell. But I anticipate that most likely I am going to get asked to do that around the April time period and I'll keep that open.
Moderator: Governor, you will plan then to release your income tax records around April?
Romney: I think I've heard enough from folks saying, look, let's see your tax records. I have nothing in them that suggests there's any problem and I'm happy to do so. I sort of feel like we are showing a lot of exposure at this point. And if I become our nominee, and what's happened in history is people have released them in about April of the coming year and that's probably what I would do.
Hmm, let's see: "I hadn't planned on releasing tax records ... time will tell ... most likely ... I'll keep that open ... that's probably what I would do". In conclusion: who knows?
Asked why he hasn't released his tax records, Mitt Romney basically says "I'll do that when I'm the nominee".
The Guardian's Suzanne Goldenberg is in the hall and sends her thoughts:
It's an anti-Romney crowd in the debate hall – judging from the loud cheers that go out every time one of his opponents sticks the knife in. From our vantage point,in the debate watching room in Myrtle Beach convention centre where there is a steady flow of reporters to the (free) popcorn machine, Rick Santorum seems to have done the most damage.
First, he put Romney on the spot to explain whether he supported the rights of convicted felons who have served their time to vote. Then, while Romney dredged his mind for the right sound bite, Santorum reminded the audience that Massachusetts had restored those rights even to prisoners on parole while Romney was governor. This was possibly Romney's most uncomfortable moment on what is shaping up to be a bad night for the Republican frontrunner.
Asked about the ideal tax rate, the candidates all fall over themselves to name low numbers. But Ron Paul outdoes them all by saying he wants taxes to be zero.
The bald guy from the Wall Street Journal lines up a zinger against Ron Paul about his desire to cut defence spending and looks very pleased with himself. But no, says Ron:
You need to understand that there is a difference between just military spending and defense spending, just to spend money. We understand this domestically. If you spend more money domestically, we know it's wrong, but we are supposed to spend more money and that's conservative. I've never quite understood this. We are supposed to be conservatives. Spend less money
Mitt Romney is looking particularly Mrs Doubtfire-like tonight.
Once again, asked how far he would go to save the financial system in a crisis, Romney just bangs on about how awful Barack Obama is because ... free markets.
Romney's abortion position is cast into doubt thanks to Buzzfeed Politics's Andrew Kaczynski in this tweet:
Hmm, Mitt didn't mention this in his answer somehow.
"We are getting questions tonight from Twitter," says Bret Baier. And the first one is: how can we believe anything you say Mitt Romney?
Romney is ready for this and tackles it by briefly skating over some selected highlights of his views on abortion and gay marriage before launching into an attack on Barack Obama.
If you listened carefully, you may have noticed that for a nanosecond Romney suggested he may have given the impression that he was at one point not violently opposed to abortion. But that was because he was running for office in Massachusetts, and you know that nothing a Republican candidate says while running for office in Massachusetts should count, right?
I couldn't really capture the full flavour of that Santorum-Romney exchange, because there was a lot going on there. Romney didn't drop himself in it but he didn't help his cause either.
Rick Santorum pokes Romney for his nasty Super Pac ad, and turns it against Romney by asking him if he thinks that felons who have served their time should able to vote.
This turns out to be a CUNNING TRAP for Romney, who answers Santorum's question by saying he doesn't think felons convicted of violent crimes should be able to vote. Oh really, says Santorum, because when you were governor of Massachusetts violent felons could even vote while they were serving time. And the bill I voted for was called the Martin Luther King Voting Act.
Zing!
This exchange goes on for some time and serves to make Romney look incredibly shifty and evasive. But hey, that's the Mitt Romney we know and love.
"I did not have a Super Pac have an ad run against you," says Romney at one point, sounding as if butter wouldn't melt in his mouth.
Santorum replies: "I would tell them to STOP IT!" and gets a big round of applause.
Actually, this is lively stuff from Santorum. Keep this up boys, and you might knock a whole percentage point off Romney's approval rating.
If you attack Bain Capital, you are attacking America – that's the gist of Romney's latest reply.
A remarkably pointed attack on Romney from Rick Perry – yes, Rick Perry – who mentions that he and Newt Gingrich are publishing their tax returns, while Romney refuses to.
In response, Romney mentions that he helped start a new steel mill somewhere. And China cheats.
Asked to respond to Gingrich's attacks on his record, Mitt Romney avoids answering any specifics about companies that may or may not have been – ah – violently assaulted by Romney's Bain Capital over the years.
Anyway it turns out Romney only ran to be governor of Massachusetts because people saw what a bang up job he did running the Winter Olympics. Because that happens, right?
On that basis, Sebastian Coe is going to be Supreme Leader of the European Union in a couple of years.
First question is to Newt Gingrich, who is asked why he made such a big deal about not making negative attacks and yet somehow seems to have done lots of negative-y attacking-yness.
Oh, it's just "raising questions" says Newt. So let's be clear: when Newt makes negative attacks they are "raising questions". But pointing out that he used to hang out with Nancy Pelosi in favour of climate change, say, that's out of bounds.
Ready, set, debate. Photograph: Charles Dharapak/AP
So here we go then, it's Fox News's Bret Baier moderating, and a few others, including a couple of wonks from the Wall Street Journal, all part of the Friendly Murdoch Family Empire.
Tonight will allow the candidates to have 90 second answers because there are now only five of them on stage. Joy.
Five minutes to go. Those unlucky enough not to have the benefit of Fox News on your cable box can follow it via live streaming on the Fox News website.
In case you were wondering why the South Carolina primary is a big deal, consider how big Romney's lead is in the forthcoming – and far more important – Florida primary at the end of the month, according to the latest polling:
Mitt Romney has jumped into a wide lead in the Florida Republican presidential primary. Romney leads with 42%, followed by Newt Gingrich with 25%, Rick Santorum with 9%, and Ron Paul with 8%.
Romney leads among registered Republicans with 42% and is followed by Gingrich with 27%, Santorum with 8%, and Paul with 6%.
Romney leads with 37% among likely Republican primary voters saying they are supporters of the Tea Party, followed by Gingrich with 22% and Santorum with 15%. Among likely primary voters saying they are not supporters of the Tea Party or are undecided about the Tea Party, Romney leads with 45%, followed by Gingrich with 27% and Paul with 10%.
Mitt Romney leads among tea party voters? That just about clinches it.
Newt Gingrich previewed his line of assault on Mitt Romney tonight at a meeting in South Carolina earlier today:
Why would you want to nominate the guy who lost to the guy who lost to Obama?
The guy in question being Mitt Romney, who lost the Republican nomination to John McCain in 2008, who lost to Barack Obama. Logical in a crazy sort of way.
And what better day than Martin Luther King Day to recall – as Buzzfeed Politics does – one of Mitt Romney's more inglorious claims as a politician:
A long-lost press release from when Mitt Romney was running for Governor airs a since retracted line about watching his father George march with Martin Luther King during the civil rights movement.
Romney says in the 2002 release, "I watched my dad march with Martin Luther King in the streets of Detroit. I was with him when he walked out of the 1964 Republican Convention because the Republican Party wouldn't accept a civil rights platform."
But Romney never saw his father march with Dr King. The line, repeated by Romney throughout his 2002 campaign and briefly throughout 2007, didn't stand up the facts.
At least Romney didn't claim to be to the left of Martin Luther King on civil rights, although he would have if he thought there was a vote in it.
Strange that tonight's debate (a) happens to be on Martin Luther King memorial day and (b) happens to be in South Carolina, where the Civil War broke out – against the Republican party.
In that light, here's a "What Do You Know About Martin Luther King?" online quiz to try while we are waiting for the debate to start at 9pm ET.
And then there's this issue:
As the Republican presidential candidates prepare for a Martin Luther King Day debate here Monday night, one longstanding issue that has yet to become a factor in this year's South Carolina primary could again rear its head: the contentious debate over the Confederate flag that flies in front of the statehouse in Columbia.
Is it just me or does that Myrtle Beach sand sculpture of the Republican candidates not look anything like any of the candidates?
Sand sculptures depicting Republican presidential candidates in front of the Myrtle Beach Convention Center. Photograph: Mark Wilson/Getty Images
One looks more like Ted Kennedy. Presumably that's meant to be Mitt Romney then. But seriously, I can't identify any of them. The one in the middle is Perry? I don't know, please leave your thoughts.
There's two vital questions at stake in tonight's Republican presidential debate in South Carolina – well, three if you count "Another debate?" as a question. The first is: Can Mitt Romney be stopped from winning the GOP presidential nomination? And the second is: Which one of the remaining losers on stage tonight is going to stop him?
One hates to (as the British say) micturate on your french fries, but the answer to the first is "no" and to the second is "duh".
Should Romney win the South Carolina primary next Saturday – and the latest polling suggests he will – then that effectively ends the GOP contest. The only way that story line is going to change is if Romney doesn't win the South Carolina primary, and probably the only way that will happen is if he is figuratively disemboweled by his debate rivals, namely Newt Gingrich, Rick Santorum, Ron Paul and Rick Perry.
That's why tonight's debate – and the following debate on Thursday, also in South Carolina – are so important for the shrinking "anyone but Romney" segment of the Republican party. Yes, shrinking, because the polls also show that Romney's approval ratings and national support are rising after his victories in Iowa and New Hampshire.
But so far in this campaign, Romney's opponents have failed to press significant attacks upon Romney's campaign or character, and Mitt himself has become pretty good at batting them away.
Anyway, make the most of this because I have a feeling there won't be too many GOP debates after tonight and Thursday.
As always, follow all the live action here once the debate itself starts at 9pm ET, with observations from the Guardian's award-winning* team of political commentators and Twitter-readers. And please leave your comments below for the benefit of pol-sci PhD thesis writers in the year 2087.
* Note: may not have actually won awards