11:00 p.m. Excerpts from the candidates' closing statements:
Paul: "Thanks for having me. It's great to be back. I'm an eye surgeon from Bowling Green, Kentucky. I miss doing eye surgeries...the thing that's most important for me and calls me to run for office is I'm worried about the country and how much debt we're adding."
Kasich: "One of our biggest national security issues is the world looks at us sometimes and we look at each other and say why can't we solve problems. I've got news for you: We can...all this has to come together when we have a positive attitude, an optimistic approach, an opportunity for us to set the tune as conservatives."
Christie: "On Sept. 11 my wife was two blocks from the World Trade Center ...terrorism in this country scares everyone and the fact is we need a commander in chief who not only understands how to protect us but feels in here how it feels to face the possibility of loss....no one will keep this country safer than I will."
Bush: "We desperately need a conservative leader as president of the United States. I have a proven record as the governor of Florida, as a leader, and I also have detailed plans to fix the mess in Washington D.C...I will defeat Hillary Clinton in November. I ask for your support in the caucuses come Monday night and I will make you proud as the party's nominee."
Carson: "I want to thank the people of Iowa for being so welcoming of me. Please think of our founding farmers as you listen." He then went on to recite the preamble to the Constitution. "Folks it's not too late. Enough said," he concluded.
Rubio: "The Bible commands us to let our light shine on the world...now that light is dimming a little after seven years of Barack Obama and that's why Monday night what will happen here in Iowa is so important...if I'm your nominee I will unite this party and I will defeat Hillary Clinton."
Cruz: "Ninety-three hours. The media noise will soon be over and it's now for the men and women of Iowa to decide. Our country's in crisis, we're worried for our children and we've been burned over and over again...examine our records, pray on it, I would be honored if you and your family would come caucus for us on Monday night."
10:50 p.m. Carson is also asked about his position on the Renewable Fuel Standard.
"Certain promises were made, certain government contracts were issued which extend all the way into the year 2022 and I believe that it's probably unfair to withdraw the rug because people have invested money, people have invested a lot of energy into that," Carson said. But he encouraged people to talk about new sources of energy.
10:48 p.m. Cruz gets a question about his opposition to the Renewable Fuel Standard and the fact that Iowa Gov. Terry Branstad has said he shouldn't be the nominee because of that position.
"I don't believe that Washington should be picking winners and losers and I think there should be no mandates and no subsidies whatsoever," Cruz said. He referred to his tax plan, which he said eliminates every mandate and subsidy.
"It is true that there are a bunch of lobbyists and a bunch of Democrats in this state trying to convince the people of Iowa that I somehow oppose ethanol. It's not true," he said.
10:44 p.m. Former President Bill Clinton is invoked as Kelly asks Paul whether it's fair to hold Hillary Clinton accountable for the sins of her husband.
"I've never really brought this up unless asked a question," Paul said. "I don't think she's responsible for his behavior but I do think her position as promoting women's rights and fairness to women in the workplace, if what Bill Clinton did, any CEO in our country did...they would be fired, they would never be hired again."
"She can't be a champion of women's rights at the same time she's got this, this kind of thing lurking out there," he said.
10:39 p.m. In response to Defense Secretary Ash Carter warning today that ISIS is consolidating in Libya, Baier asked Christie whether he would send in U.S. troops there.
"This is another one of those places whre Hillary Clinton has so much to answer for and why she is completely unqualified to be commander in chief," Christie said. "This is about the bigger broader war against ISIS. We need to bring togehte rour European and our Sunni Arab allies and we need to develop a strategy to take out ISIS everywhere it is."
10:33 p.m. In response to Russian President Vladimir Putin's incursion into Ukraine, Carson calls on the U.S. to give the Ukrainians offensive weapons, restore the old missile defense system in the region, and said he would abide by U.S. treaty obligations to defend Ukraine from an attack.
10:32 p.m. Paul also weighed in on faith and governance in a broader sense.
"On the broader question of religion in politics, I think liberty itself requires a virtuous people...without the religious foundation that guides us all I think we have a great risk of going in the wrong direction," he said.
Unfortunately, he was asked about his past statements saying abortion should be a state issue, and Wallace pressed him for an answer on that.
Paul said he supports "Both a federal and a state approach. I have said we could leave it to the states but I've also introduced a federal solution as well, he said, referring to his Life at Conception Act which he said would "federalize" the issue.
10:29 p.m. Rubio delivers a passionate defense of faith in public life, arguing that America's "Judeo-Christian values" are what makes the country great.
"You should hope that our next presidnet is someone who is influenced by their faith...my faith will not just influence the way I'll govern as president, it will influence the way I live my life," he said.
10:28 p.m. Christie turns a question about Kim Davis, the Kentucky clerk who refused to issue same-sex marriage licenses, into a warning about ISIS.
"The radical Islamic jihadists what they want to do is impose their faith on each and every one of us," he said.
10:20 p.m. Christie is asked whether it's too risky to nominate him because his former aides are preparing to go on trial for their role in the Bridgegate scandal.
"Sure, because there have been three different investigations that have proven I knew nothing," he said.
10:18 p.m. Sen. Bernie Sanders, I-Vermont, one of the other Democratic candidates gets a rare mention during the GOP debate.
"I think Bernie Sanders is a good candidate for president. Of Sweden," Rubio quipped.
10:17 p.m. Kelly notes that most of Bush's Republican opponents perform better than him in head-to-head polling match ups against Clinton. Are his attacks merely hurting his colleagues who have a better chance of beating her, she asked.
"I've seen polls where I'm beating Hillary Clinton pretty regularly and I believe I can," Cruz said. "I'm confident if I win this nomination I will aggressively go against her and beat her. As it related to the super PACs I have no control over that and this is beanbag compared to what the Clinton machine is going to do to the Republican nominee."
10:15 p.m. Cruz is asked about his lack of popularity among his Senate colleagues.
"Does your style sometimes get in the way of your ability to get things done?" moderator Chris Wallace asked.
"You are exactly right that I am not the candidate of career politicians in Washington," Cruz responded. "The endorsements I am proud of are the over 2,000 volunteers across this country who have signed up to volunteer for our campaign."
"If I am elected every single day I will do two things: Tell the truth, and do what I said I would do," he added.
10:14 p.m.A Mexican immigrant who served in the U.S. armed forces, became a citizen, and is now an entrepreneur, asked about the place of immigrants in the U.S. economy given the tone of some Republicans.
Asked to respond, Carson shifts to talking about ISIS.
"We are a land of immigrants but we have to be intelligent about the way we form our immigration policies," he said. He said the U.S. should "declare war on the Islamic state because we need to reorient our immigration policies and our visa policies for people who are coming into this country because there are many people out there who want to destroy us."
10:07 p.m. Paul says that Cruz has an "authenticity problem" because he suggests he was the only person who opposes amnesty.
"It's a falseness and that's an authenticity problem that everybody he knows is not as perfect as him because we're all for legalization...so was Ted," he said.
In his defense, Cruz repeatedly invokes Sen. Jeff Sessions, R-Alabama, who has been a vocal opponent of most immigration reform legislation and wants to lower levels of immigration to the U.S.
Rubio also piles on. "You want to trump Trump on immigration," he charges, saying the GOP can't nominate someone who will do anything to win.
Christie uses the discussion to make one of his frequent arguments: That Republicans should nominate someone from outside of Washington who doesn't just engage in congressional debates.
"Stop the Washington bull and let's get things done," he said.
10:04 p.m. Cruz gets the past-video-statements treatment as Kelly plays several clips where he said he was trying to save the 2013 Senate immigration bill. He has since said he was trying use a poison-pill amendment to kill it.
"Was that all an act? It's pretty convincing," she said.
Cruz said he was trying to fix individual problems with the bill, but that doesn't mean he supported the entire thing.
"Taking citizenship off the table was important and it revealed the hypocrisy" of the bill's authors, he said.
10:02 p.m. Bush referenced his book, "Immigration Wars," about policy. Rubio sensed an opening.
"That is the book, Rubio said, "where you changed your position on a path to citizenship."
"So did you," Bush responds, smiling.
9:59 p.m. Kelly plays a series of clips showing Rubio in 2009 and 2010 talking about his opposition to legalizing people who came to the U.S. illegally. Asked what changed, Rubio said he has always opposed an "almost instant path forward" with very few obstacles for people.
Bush compliments Rubio, saying he "led the charge" to fix the immigration system -- but then says the Florida senator "cut and run" because it wasn't popular among conservatives.
9:52 p.m. Kasich is asked how as governor he would have handled the crisis over lead in Flint, Michigan's drinking water.
"You've got to be on top of it right away," he said. "I know there are people who have been fired, people who are being held accountable, but the fact is every single engine of government has to move when you see a crisis like that."
9:49 p.m. Christie is asked to name something he would cut entirely from the federal budget.
"How about one I've done in New Jersey for the last six years and that's get rid of Planned Parenthood funding," he said.
Asked for something bigger than that, he said, "When you see thousands upon thousands upon thousands of children murdered in the womb, I can't think of anything bigger than that."
9:41 p.m. Bush is asked whether the government should police private charities that claim to help veterans in the wake of investigations -- including one from CBS News -- that reveal the organization spends a huge amount of money on things like hotel rooms and conferences.
"Of course," Bush said. He also said the "first duty" of the next president will be to "fix the mess of the Department of Veterans' Affairs."
9:39 p.m. Kasich ducks a question on whether the government needs a "back door" to encrypted communications in order to track terrorists. Government officials have argued they do.
"It;s best not talk any more about back doors and encryption. It will get solved, but it needs to be solved in the situation room of the White House," he said. "I just have to tell you it's best some of these things not be said."
9:36 p.m. Christie and moderator Megyn Kelly spar over what constitutes profiling in reference to the San Bernardino terror attacks. Christie argues that people should use "common sense" and allow law enforcement to decide what constitutes a threat.
"That can be done without profiling people. That's common sense," he said.
He also criticized Mr. Obama and Clinton, saying they have "made law enforcement the enemy."
9:34 p.m. Paul goes after Rubio on immigration, saying that Rubio struck a deal to oppose conservative amendments while the 2013 Senate immigration reform bill was being written. That included a bill from Paul to apply heightened scrutiny to people seeking to come to the U.S. as students and through other avenues.
Rubio said that everyone supports more scrutiny, but that "Rand's amendment was not the right way to do it."
9:31 p.m. Both Rubio and Bush have said the U.S. rules of engagement are hampering the military unnecessarily and preventing them from successfully taking on U.S. enemies abroad.
9:29 p.m.The audience lets out a big "boo" when Cruz said that the last several questions invited his opponents to attack him.
"If you guys ask one more mean question, I might have to leave the stage," he said.
9:26 p.m. Given the opportunity to attack his fellow Republicans on national security, Christie instead turned the focus on Clinton and talked about when she was asked about her email use at a Democratic town hall earlier this week.
"She did it for convenience, for her convenience," Christie said. "She put America's secrets at risk for her convenience. She put American intelligence officers at risk for her convenience...let me tell you who's not qualified to be president of the United States, Chris. Hillary Rodham Clinton did that to our country she is not qualified to be president of the United States."
9:16 p.m Cruz is asked whether his record matches his rhetoric on fighting ISIS. He has promised to carpet bomb the group, but did not support President Obama's request for military action to enforce his red line in Syria, and has not voted for the defense authorization bill the last three times it was on the floor.
Cruz said his promises are "not tough talk" but rather a "different fundamental military strategy" than Mr. Obama has put forward.
9:12 p.m. The moderators asked Paul whether he should have done more to embrace his father, former presidential candidate and Rep. Ron Paul. Cruz recently released a video portraying himself as the heir to Paul's liberty-minded message and the former congressman also recently said it was "realistic" that Trump could win the nomination.
Paul said he's "always had a great deal of respect" for his father and called him "probably the most honest man in politics than we've ever seen."
He also said he doesn't think his father's supporters will necessarily support Cruz.
"We had an audit the Fed vote, which was the biggest thing my dad advocated for...Ted didn't show up," Paul said. He also criticized Cruz's record on NSA reform.
Cruz said he was an original sponsor of the bill to audit the Federal Reserve, but that it "didn't have the votes to pass" and had to be at a town hall in New Hampshire the day of the vote.
"I look forward to signing that bill as president," he said.
9:08 p.m. Bush jokes that Trump was "like a big teddy bear" to him and swipes at his GOP colleagues, saying, "everyone else was in the witness protection program" except him when it came to taking on Trump.
9:06 p.m. Asked about how he will unite the GOP, Rubio instead launches into an attack on President Obama and Democratic candidate Hillary Clinton.
"Barack Obama wants America to be more like the rest of the world," he said. He also referred to Clinton's statement that she would consider nominating Mr. Obama to the Supreme Court.
"The guy who systematically and habitually violates the Constitution and the Supreme Court? I don't think so," Rubio said.
9:03 p.m. Cruz is given the first opportunity to respond to Trump's absence from the debate. He kicks off by complimenting Iowans.
He promises that if he is elected, "Iowa in 2017 will not be flyover country. It will be fly-to country."
Then he moved on to addressing Trump.
"I'm a maniac and everyone on this stage is stupid, fat and ugly. And Ben, you're a terrible surgeon," he said, gesturing to Carson and joking about insults that have been hurled at his fellow candidates.
"Now that we've gotten the Donald Trump portion out of the way, I want to thank everyone here for showing the people of Iowa the respect" to show up and debate, Cruz said.
8:45 p.m.The Republican presidential candidates are about to take the stage in Des Moines for the seventh debate of the 2016 election cycle and the final meeting before the Iowa caucuses take place Monday.
But the real story of this debate is the fact that the party's frontrunner, businessman Donald Trump, will not be on stage because of his ongoing feud with Fox News. Though Trump qualified for the main debate stage, he later refused his invitation after airing complaints about the network and Fox News debate moderator Megyn Kelly, saying the network anchor is "really biased against" him.
Instead, Trump announced, he'll hold a competing event in Iowa, just three miles from the debate venue, that will benefit veterans on Thursday night. Two of the participants in the undercard debate, former Arkansas Gov. Mike Huckabee and former Pennsylvania Sen. Rick Santorum, will join him.
Those who will be on stage include Texas Sen. Ted Cruz, Florida Sen. Marco Rubio, retired neurosurgeon Ben Carson, former Florida Gov. Jeb Bush, New Jersey Gov. Chris Christie, Ohio Gov. John Kasich, and Kentucky Sen. Rand Paul.
Earlier in the evening, Santorum, Huckabee, former Hewlett-Packard CEO Carly Fiorina and former Virginia Gov. Jim Gilmore participated in the undercard debate. Read coverage here.
The lineup boosted Paul to a main stage appearance. The Kentucky senator skipped the last GOP debate when he was relegated to a lower-tier slot. Jim Gilmore also advanced to a spot in the earlier debate.
The candidate lineup was based on the results of national, New Hampshire and Iowa surveys released before 5 p.m. ET on Tuesday, Jan. 26.
To qualify for the top-tier debate stage, a contender had to place in the top six in an average of recent national polls, or in the top five in an average of recent Iowa or New Hampshire surveys. The earlier debate included candidates who received a minimum of 1 percent in at least one recent national poll.