Republicans took the gloves off for their fifth presidential debate in Las Vegas. Focusing almost entirely on foreign policy and national security, big divides were evident in how each candidate would handle the threat of terrorism and deal with foreign leaders.

The man at the center of the stage, Donald Trump, found himself frequently challenged by several candidates, but none more harshly than Jeb Bush. While the former Florida governor had struggled to find his footing at the first several debates, Bush finally seemed to land punches against the GOP frontrunner, fighting back forcefully especially against Trump's controversial call to stop any Muslims from coming into the U.S.

The rising Texas Sen. Ted Cruz also found himself challenged by his fellow Senate colleague, Florida's Marco Rubio. The two exchanged some tense barbs on government surveillance, immigration and how to deal with Syrian President Bashar al-Assad. But Cruz had some help, finding himself frequently backed up by Kentucky Sen. Rand Paul.

Neurosurgeon Ben Carson, who's seen his support slip in the past month as questions over his ability to deal with foreign policy crises grew, did himself no favors during the CNN debate. Though he was given ample opportunity to show he had a grasp of complex foreign situations, his answers were often muddled and off-topic.

New Jersey Gov. Chris Christie, who's gotten some momentum in New Hampshire, was happy to tout his national security credentials though, reminding viewers at nearly every turn that he had prosecuted terrorists as a U.S. attorney.

Paul, along with Ohio Gov. John Kasich and former Hewlett-Packard CEO Carly Fiorina, struggled to fit into the conversation all evening though, and that's reflected in the final numbers. According to NPR's analysis, the trio, all lagging in the polls, got the least amount of time to talk.

Terrorism was also the main topic at the evening's undercard debate, where South Carolina Sen. Lindsey Graham took a hardline stance against foreign threats and promised swift military action.

You can read our full liveblog of Tuesday's main stage debate below.

11:15 p.m. Trump's last statement is familiar from his rallies: "Our country doesn't win anymore.....If I'm elected president we will win again. We will win a lot. And we're going to have a great, great country, greater than ever before."

Carson sounds a hopeful note — and away from foreign policy that tripped him up throughout the debate: "My mother told me if I work hard and I believed in American principles and I believed in God that anything is possible. I believe that is true and that's why I'm not anxious to give away American values and principles for the sake of political correctness."

11:10 p.m. Cruz's closing argument — we must take on Islamic terrorism and we need leadership back in the White House.

Rubio: "This election is about electing a president that will restore our economic vibrancy so that they American can expand to reach more people and change more lives than ever before."

Bush frames his last statement by asking the audience who is best to take on Clinton: "My detailed plans will fortify our national and economic security and my proven record as governor will give you a sense that I don't make false promises I deliver real results."

11 p.m. Closing statements — Paul argues that the national debt is threatening national security. Christie reminds people of his experience as a U.S. attorney and leadership after 9/11. Kasich says no GOP nominee has won the nomination without carrying Ohio.

10:55 p.m. A sigh of relief for GOP leaders — Trump says again he won't run as an independent in the general if he doesn't get the GOP nomination. He says he's still leading in polls though and expects to be the Republican nominee. He also says recent polls show he's leading Hillary Clinton — something that isn't true.

10:50 p.m. Those waiting for a Cruz vs. Trump smackdown will be disappointed. When asked about his comments this past weekend calling Cruz a "maniac," when it leaked that Cruz had criticized him at a private fundraiser, Trump demures. He says Cruz has "a wonderful temperament — he's just fine, don't worry about it" and that they've bonded over the past few days apparently.

But how does Cruz feel? Does Trump have the necessary judgement to be commander in chief? He says it's up to voters to decide that.

10:45 p.m. Another puzzling answer to a foreign policy question from Carson. He's asked specifically about North Korean leader Kim Jong Un, but turns it into an answer about Russia: "We also recognize that North Korea is in severe financial straits and they have decided to use their resources to build their military instead rather than to feed their people and to take care of the various humanitarian responsibilities that they have. We can capitalize upon that. You know, we should use our economic power in lots of different ways. I think we can use that in order to keep Putin contained because he's a one-horse show: energy."

10:30 p.m. Cruz vs. Rubio, round two on immigration. Rubio points out that Cruz supposed an increasing in H1B visas, increasing guest workers and green cards. Cruz says that's false and that "Marco wants to raise confusion."

"He was fighting to grant amnesty and not to secure the border. I was fighting to secure the border," Cruz pushes back.

10:20 p.m. Another Bush vs. Trump skirmish breaks out as Bush tries to paint Trump as weak on foreign policy.

"I would seek out, as I have, the best advice that exists," Bush says on his foreign policy approach. "I won't get my information from the shows I don't know if that's Saturday morning or Sunday morning."

Trump starts attacking the media and CNN for loaded questions asking candidates, in both this debate and the previous undercard debate, about his proposals specifically. "I think it's very said. I think it's unprofessional," Trump says.

Bush says if Trump can't handle these questions, "what it's going to be like dealing with Putin, dealing with President Xi or dealing with the Islamic terrorism that exists. This is a tough business."

Trump's response — you're not so tough Jeb: "I'm at 42 and you're at 3 so so far I'm doing better," he retorts, citing his poll numbers.

10:15 p.m. Christie goes all "Jersey tough" on how he'd deal with Russia. "I would make very clear I wouldn't not talk to Vladimir Putin, In fact., I would talk to Vladimir Putin a lot and I would say to him, 'Listen Mr. President, there's a no- fly zone in Syria. You fly in it applies to you ,and yes we would shoot down the planes of Russian pilots.'" and bashes Obama as a "feckless weakling."

The far more isolationist Paul jumps in, saying Christie is trying to start World War III, branding him a bully and hearkening back to his Bridgegate scandal.

10:10 p.m. Here's Kasich on how he'd deal with foreign policy in the volatile region: "For the Russians, frankly it's time that we punched the Russian in the nose. They've gotten away with too much in this world and we need to stand up against them not just there but also in Eastern Europe where they threaten some of our most precious allies."

10:05 p.m. More differences on foreign policy — Cruz stands by saying he would leave Bashar al-Assad in power for fear Syria would fall to ISIS. Rubio says he "wouldn't shed a tear" if he was gone.

Trump sides with Rubio on this one: "We have to do one thing at a time. We can't be fighting ISIS and fighting Assad. Assad is fighting ISIS. He's fighting ISIS. Russia is fighting now ISIS and Iran is fighting ISIS. We have to do one thing at a time," he says.

Paul later sides with Cruz saying he doesn't think right now is a time for regime change.

9:55 p.m. The CNN moderators are giving Carson plenty of time to try and show his foreign policy bona fides — something that's been questioned on the record by his own advisers since the last debate. But his answers have been jumbled and hard to follow. Here's part of his comment on ISIS: "Take their oil, shut down all the mechanisms whereby they can disperse money because they go after disaffected individuals from all over the place and they are able to pay them that makes a difference ... we've got a phobia about boots on the ground. If our military experts say we need boots on the ground, we should put boots on the ground."

9:50 p.m. Fiorina, also frustrated with a lack of time and opportunity to jump in to outline her plans to combat ISIS, ticks off generals she's worked with and would consult. She channels Margaret Thatcher as the only woman on the stage: "If you want something talked about, ask a man. If you want something done, ask a woman."

9:45 p.m. Paul, who's directed his time almost entirely at attacking Trump, also questions whether Bush is a serious candidate and points out the First Amendment doesn't let you close the internet and the Geneva Convention doesn't let you kill innocent citizens. "It would defy every norm that is America. So when you ask yourself whoever that think you're going to support Donald Trump think do you believe in the Constitution are you going to change the Constriction?" he says.

9:40 p.m. Bush jumps in saying these proposals from Trump make him not serious. The two bicker back and forth, and Bush tells Trump, "You are not going to be able to insult your way to the presidency." Trump yells at Bush for interrupting him and says he should apologize.

9:35 p.m. Two things Trump isn't backing away from — his idea to close parts of the internet and to target ISIS family members. " "We should be using our most brilliant minds to figure out a way that ISIS cannot use the internet...I don't want them using our internet."

Later in response to a question from a college student about killing ISIS family members, he doesn't walk it back either. "I would be very, very firm with families and frankly, that will make people think. Because they may not care much about their lives, but they do care, believe it or not, about their family's lives."

9:27 p.m. Christie jumps in, trying to portray himself as the adult in the room and certainly not a part of the dysfunctional Senate.

"If your eyes are glazing over like mine this is what it's like to be on the floor of the United States Senate," he says to laughs. "The fact is for seven years I had to make these decisions after 9/11 about how to proceed forward with an investigation or about how to pull back whether to use certain actionable intelligence or whether not to. And yet they continue to debate about this bill and then the subcommittee and what? Nobody in America cares about that. What they care about is are we going to have a president who actually knows what they're doing to make these decisions."

9:23 p.m. Carson gets a follow-up about the question of data collection between the senators — and he complains about not getting a question until now, then really doesn't answer it. "We have to get rid of all this PC stuff and people are worried about somebody's gonna say that I'm Islamophobia or what have you," he said. "This is craziness because we are at war. That's why I asked Congress go ahead and declare the war."

9:20 p.m. Cruz gets an assist in going after Rubio from Paul, who agrees with him on data collection.

"Marco can't have it both ways 00 he thinks he wants to be this 'Oh, I'm great and strong on national defense' but he's the weakest of all the candidates on immigration," Paul says. "He is the one for an open border that is leaving us defenseless ... Marco has more of an allegiance to Chuck Schumer and to the liberals than he does to conservative policy."

9:15 p.m. The question of government surveillance and its role in fighting terrorism sets up a huge clash between Rubio and Cruz. Rubio slams his fellow senator for supporting the USA Freedom Act, which extended some PATRIOT Act provisions but not the ability to collect and keep bulk data.

"What the Obama administration keeps getting wrong is whenever anything bad happens they focus on law abiding citizens instead of focusing on the bad guys. We need to focus on radical Islamic terrorists and we need to stop them before they carry out acts of terror," Cruz says.

9:05 p.m. Trump's first question is, predictably, about his controversial proposal to stop any Muslims from coming into the country. "We are not talking about isolation — we're talking about security. We're not talking about religion, we're talking about security," he argues, emphasizing his plan to build a wall along the Southern border.

Bush — who has struggled in past debates — defends his previous comments that Trump's proposal was "unhinged" and says it would actually hurt the U.S. by making it harder to work with allies — something Hillary Clinton also argued earlier today.

"Donald, you know, is great at one liners, but he's a chaos candidate and he'd be a chaos president. He would not the commander in chief we need to keep our country safe," Bush said, in one of his stronger moments in debates yet.

Trump fired back by dissing Bush's struggling campaign, saying he doesn't really believe that. His campaign's "been a total disaster, nobody cares," Trump says.

8:58 p.m. Cruz goes directly after President Obama for not calling terror threats "radical Islamic terrorism." More Cruz: "If I'm elected President we will hunt down and kill the terrorists. We will utterly destroy ISIS. We will stop the terrorist attacks before they occur because we will not be prisoners to political correctness." Carson opens with a moment of silence for the San Bernardino victims and talks about how he kept people safe as a physician.

8:55 p.m. Other opening statements — Christie reminds voters he's prosecuted terrorists as U.S. attorney and would be the toughest president. "America has been betrayed we've been betrayed by the leadership that Barack Obama and Hillary have provided this country over the last 5 years."

Rubio reminds voters he lived in Nevada as a child, telling his story of climbing from a poor immigrant family to the Senate.

8:50 p.m. Paul begins opening statements by taking a shot at Trump, essentially comparing him to a foreign dictator. "Trump says we ought to close that internet thing the question is what does he really mean by that? Like they do in North Korea? Like they do in China?" He says he would keep America safe, but also underscores it has to be done in concert with the Bill of Rights (whose birthday is today!) His libertarian strain is going to make it hard for him in this changed GOP primary though — and one reason he barely made the main debate stage.

Copyright 2015 NPR. To see more, visit NPR.

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