Nine candidates are set to take the stage for the fifth prime-time Republican debate of the year.
Here are the candidates who will be on stage: Real-estate mogul Donald Trump, Sen. Ted Cruz (R-Texas), Sen. Marco Rubio (R-Florida), former Florida Gov. Jeb Bush (R), Sen. Rand Paul (R-Kentucky), retired neurosurgeon Ben Carson, Ohio Gov. John Kasich (R), New Jersey Gov. Chris Christie (R) and former Hewlett-Packard CEO Carly Fiorina.
For the second consecutive debate, former Arkansas Gov. Mike Huckabee (R) was relegated to an an earlier, "undercard" debate.
See images from the debate:
He he joined Sen. Lindsey Graham (R-South Carolina), former Sen. Rick Santorum (R-Pennsylvania), and former New York Gov. George Pataki (R).
The main affair could get chippy, as candidates look to improve their standings with fewer than 50 days before the first votes are cast in the primary process.
Check out our continuous coverage below:
11:00 p.m. — Christie again mentions that his wife worked near the World Trade Center on September 11, 2001, a familiar story that he tells on the campaign trail.
10:55 p.m. — Trump reiterated that he would not run as an independent, and would commit to running as a Republican.
"Are you ready to reassure Republicans tonight that you are ready to run as a Republican and abide by the decision of the Republicans?" Moderator Hugh Hewitt.
"I really am," Trump responded.
10:47 p.m. — Talking about the hack of the Office of Inspector General that exposed the personal information of potentially millions of federal employees, Bush said that it was possibly a good thing that members of the press had their information stolen as well.
"Maybe that's the only part that's good news, so that you guys can get a feel for what it's like now to see this type of attack," Bush said, gesturing to reporters.
10:36 p.m. — Kasich laid out why he would pause the entry of Syrian refugees into the US, despite the fact that people allegedly accuse Kasich of having "too big a heart."
"Look, people have accused me at times of having too big of a heart. You know, that's OK. But I have to also say, I must keep the people of my state safe, so take a pause," Kasich said.
10:33 p.m. — When asked if he'd send refugees home, Paul dodged the question.
"I haven't taken a position on sending anyone home," Paul said.
10:16 p.m. — Bush mocked Trump's past admission that he gets some of his foreign policy advice from the Sunday morning political shows.
"I won't get my information from 'the shows.' I don't know if that's Saturday morning or Sunday morning. I don't know which one," Bush said, a reference to Saturday morning cartoons.
Trump scoffed at Bush's comments, mentioning that his poll numbers were far higher than the former governor's.
10:09 p.m. — After several debates of hedging slightly on foreign policy questions, Paul coherently laid out his libertarian-minded foreign policy approach to Syria and Iraq, warning against increased military intervention without a clear strategy for managing the situation.
"We have to have a more realistic foreign policy, and not a utopian one where we say, 'Oh, we're going to spread freedom and democracy and everybody in the Middle East is going to love us," Paul said. "They're not going to love us."
After Christie said that he'd be willing to institute a no-fly zone in Syria, and would shoot down Russian planes flying in the region, Paul hit Christie.
"If you're in favor of World War III, I think you've got your candidate," Paul said.
10:06 p.m. — Cruz attempted to talk over CNN co-moderator Hugh Hewitt. As Cruz continued to speak, he was met with a few scattered boos from the audience.
10:02 p.m. — After Trump said that the US should not be exhausting the federal budget overseas with military conflict, Fiorina slammed Trump.
"That's exactly what President Obama said. I'm amazed to hear that from a Republican presidential candidate," Fiorina said.
9:46 p.m. — When asked about if he would be ready to order airstrikes that would kill civilians, Carson made an analogy to his time performing brain surgery on young children.
"We're going to have to open your head up and take out this tumor," Carson said.
"They're not happy about it believe me and they don't like me very much at that point," Carson said of meeting with his young patients. "But later on, they love me."
Hewitt then asked if Carson would be "OK with the deaths of thousands of innocent children and civilians?"
"You got it. You got it," Carson responded.
9:45 p.m. — Trump's suggestion that he would shut down parts of the Internet where suspected terrorists communicate was met with boos. Scoffing at hostile members of the audience, the real-estate mogul immediately responded.
"These are people that want to kill us, folks," Trump said. "And you're objecting to us infiltrating their conversations? I don't think so. I don't think so."
9:37 p.m. — Trump and Bush had a heated back-and-forth about immigration and Trump's suggestion that families of terrorists should be punished for their family members' actions.
"Two months ago, Donald Trump said that ISIS was not our fight," Bush said.
"And he gets his foreign policy experience from the shows. That is not a serious kind of candidate. We need someone that thinks this through that can lead our country to safety and security."
The exchange quickly devolved into personal attacks.
"I know that you're trying to build up your energy, Jeb, but it's not working," Trump said.
"Donald, you're not going to be able to insult your way to the presidency," Bush responded moments later.
9:31 p.m. — Cruz said that the US government's "political correctness" prevented the government from identifying social media posts that could've tipped off law enforcement before the attack in San Bernardino, California that left 14 people dead.
"Political correctness is killing people," Cruz said.
Despite Cruz's assertion that the female San Bernardino shooter Tashfeen Malik made a "public call to jihad," news outlets including CNN reported this week that Malik's social media messages about jihad were posted on a private Facebook profile using a pseudonym.
9:26 p.m. — Trump said that he would be "open to closing down" parts of the Internet where suspected terrorists communicate.
"I don't want them using our Internet," Trump said.
"We should be using our brilliant people, our most brilliant minds, to figure out how ISIS cannot use the Internet."
Kasich got a chance to respond, saying that Trump's suggestion was not a good idea.
9:20 p.m. — Christie mocked Cruz and Rubio's back-and-forth over the USA Freedom Act, saying that it was typical of the argumentative nature of Congress.
"If your eyes are glazed over like mine, this is what it's like to be on the floor of the US Senate," Christie said.
9:14 p.m. — Rubio and Cruz had a quick exchange about the USA Freedom Act, a bill passed earlier this year which curbed the National Security Agency's dragnet telephone metadata surveillance program. Rubio slammed Cruz for supporting the bill.
"Marco knows what he's saying isn't true," Cruz said. "You know, Mark Levin wrote a column last week that says that the attack ads his super PAC are running are saying the same thing: That they are knowingly false, and they are in fact Alisky-like attacks like Barack Obama."
Paul also jumped in, disagreeing with Rubio as well.
"Rubio has more allegiance to Chuck Schumer and liberals than the Republican party," Paul said.
9:12 p.m. — Kasich criticized the Paris Climate Conference, saying that the US should have been involved in a conference to build a military coalition against ISIS in Syria.
9:05 p.m. — Cruz dodged a question from co-moderator radio host Hugh Hewitt about why he said that he disagreed with Trump's plan to ban Muslims from coming to the US.
"Everyone understands why Mr. Trump has suggested what he has," Cruz said.
9:02 p.m. — Bush criticized Trump's plan to ban Muslims from coming to the US.
"Donald is great at the one-liners, but he's a chaos candidate and he'd be a chaos president," Bush said. "He would not be the commander in chief we need to keep our country safe."
8:57 p.m. — During his opening statement, Carson asked the audience for a moment of silence for the victims of a shooting in San Bernardino, California that left 14 people dead.
8:55 p.m. — In his opening remarks, Rubio recalled when his grandfather talked to him about the state of the nation, smoking three cigars a day.
8:49 p.m. — Paul slammed Trump in his opening statement, citing Trump's suggestion that the US may need to shut down parts of the Internet to combat religious extremists.
"The question is — how do we keep America safe from terrorism? Trump says we outta close down 'that Internet thing,'" Paul said. "The question really is — what does he really mean by that? Like they do in North Korea? Like they do in China?"