Miami(CNN) In their last debate before Tuesday's important primary and caucus contests in Florida, Illinois, Missouri and Ohio, Republican presidential candidates split over a host of key issues, including worker visas, Social Security, Islam and foreign policy.
Donald Trump defended his claim that "Islam hates us" during CNN's debate here Thursday.
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The GOP front-runner stirred up fresh controversy this week when he said in an interview with CNN's Anderson Cooper, "I think Islam hates us." He claimed that there was "tremendous hatred" that partially defined the religion, and that while the United States is focused on fighting radical Islam, "it's very hard to define. It's very hard to separate. Because you don't know who's who."
When debate moderator Jake Tapper asked Trump to clarify those remarks and whether he was referring to all Muslims, Trump responded: "I mean a lot of them."
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"There's tremendous hatred and I will stick with exactly what I said to Anderson Cooper," he said.
Marco Rubio, who is struggling to keep his campaign afloat, jumped in to criticize Trump. The Florida senator argued it's not presidential to say things without thinking through the ramifications.
"Presidents can't just say what they want. It has consequences," Rubio said.
"I don't want to be so politically correct," Trump said. "It would be very easy for me to say something differently, and everyone would say, 'Oh, isn't that wonderful?' We better solve the problem before it's too late."
Rubio shot back: "I'm not interested in being politically correct. I'm interested in being correct."
The candidate argued that weeding out radical Islam cannot happen without cooperation from Muslim allies. "We are going to have to work with people of the Muslim faith," he added.
The GOP candidates are heading into a week that could alter the course of the 2016 election. The CNN debate was the final time the four hopefuls will meet before major states including Ohio, Florida and Illinois head to the polls on Tuesday.
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Trump is dominating the race, but it's still unclear whether he'll have enough delegates to secure the GOP nomination before the Republican convention this summer. Addressing all of the recent buzz about the possibility of a contested or brokered convention, Trump said the party should crown whomever ends up with the most delegates.
"First of all, I think I'm going to have the delegates, OK?" Trump said. "I think that whoever gets the most delegates should win. That's what I think."
Ted Cruz, who is currently in second place in the delegate race, chimed in that choosing anyone other than the candidate with the most delegates would be "absolute disaster."
Establishment Republicans "want to parachute in their favorite Washington candidate to be the nominee," Cruz said. "We need to respect the will of the voters."
A week after the last raucous Republican debate at which Trump boasted about the size of his manhood, Thursday's forum lacked the personal insults that overwhelmed many of the previous showdowns.
"I cannot believe how civil it's been up here," Trump said at one point in the evening.
That dynamic had the effect of making it difficult for John Kasich to find his spark. The Ohio governor, who is hoping for a victory in his home state, has insisted on staying above the fray as his foes have wrestled in the mud. The civil tone was also a shift for Rubio from last week, when he relentlessly mocked Trump on everything from his hair to the size of his hands. The senator appeared more comfortable having returned to his usual demeanor.
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The only sparks that flew between the candidates at Thursday's prime-time event were about policy, including immigration, Social Security and foreign policy.
Cruz hit Trump over previous comments that he wants to remain "neutral" about the Israeli-Palestinian conflict so he could broker a deal as president.
The Texas senator also sought to bolster his own pro-Israel credentials, insisting he "will not be neutral" as president.
Trump rejected the criticism, saying, "There is nobody on this stage more pro-Israel than I am."
"I will say I'm pro-Israel," Trump said. "But I would at least like to have the other side think I'm somewhat neutral as to them so we can maybe get a deal done."
Another area where the candidates disagreed was climate change.
Kasich said he believes human activity contributes to climate change, but that nevertheless, it is possible to have stringent environmental rules without hurting the economy. Rubio said climate change was nothing new, and insisted that there is no law that Washington could pass that could "change the weather."
It was clear throughout the evening that Trump entered the debate with a deliberate intention of toning down his usual boisterous rhetoric. On multiple occasions, the candidate was asked about controversies that have inflamed his campaign -- each time, Trump responded calmly.
For example, Trump said he had heard about a protester getting punched by an attendee at his campaign rally this week, but that he had not seen the video. Even though he has on multiple occasions seemingly encouraged violence against protesters, Trump insisted Thursday night that he did not support this kind of behavior.
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"I certainly do not condone that at all," Trump said.
He added: "We have some protesters who are bad dudes. They have done bad things."
Trump was asked about his recent comments that appeared to endorse authoritarian leaders and political regimes.
On the Tiananmen Square protests that broke out in China in 1989, Trump said he believed the Chinese government had a "strong, powerful" response that "kept down the riot." On Russian President Vladimir Putin, Trump said he has been a "strong leader for Russia."
"That doesn't mean I'm endorsing Putin," Trump said. "Strong doesn't mean good."
The evening once again exposed Trump's lack of depth on various policy issues.
When the candidates were asked how they would try to reform Social Security, Cruz and Rubio suggested that Trump's proposal --- " I will do everything within my power to do nothing to Social Security" --- lacked substance.
"The numbers don't add up," Rubio said, saying even after getting rid of fraud and abuse, there would still be hundreds of billions of dollars needed to close the gap.
Cruz also suggested that Trump's solution amounted to a magic pill.
"We've got lots of challenges in the world but the answer can't be, wave a magic wand and problem, go away," Cruz said.
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Trump bristled, accusing Cruz of having flip-flopped on ethanol subsidies for political expediency.
"Ted did change his view and stance on ethanol quite a bit," Trump said, "in the hopes of maybe doing well."
Cruz shot back by criticizing Trump -- as he has in previous debates -- for having contributed to Democrats in the past. He said Trump has not shown that he would truly stand up to special interests in Washington and that it was hard to imagine how his rival would "suddenly" change course.
"First of all, Ted was in favor of amnesty," Trump said.
Another issue that put Trump on the spot Thursday was H-1B visas, which encourage legal immigration for high-skilled workers.
Trump, who has been inconsistent on the program in the past, called it "very, very bad for workers." But in the same breath, acknowledged that he uses it in his hiring practices.
Saying that the program should simply not exist, Trump quipped: "I know the H-1B very well. I use it. I shouldn't be allowed to use it."