But before the March madness unraveled, the debate kicked off with a moment of silence in honor of the late Nancy Reagan.
Here are the best lines of the debate hosted by CNN at the University of Miami:
ON THE 2016 PRESIDENTIAL ELECTION
ON BEN CARSON
TRUMP: “I was with Dr. Ben Carson today, who is endorsing me, by the way, tomorrow morning.”
Retired neurosurgeon Ben Carson told ABC News Thursday he is leaning in the direction of endorsing Trump.
KASICH: “We ought to get them to pursue their God-given talents and connect them with the things that give them passion.”
ON SOCIAL SECURITY
SEN. MARCO RUBIO: “There are about 3 million seniors in Florida, with Social Security and Medicare. One of them is my mother, who happens to be here today. I'm against any changes to Social Security that are bad for my mother.”
TRUMP: “I want you to understand the Democrats, and I've watched them very intensely, even though it's a very, very boring thing to watch, that the Democrats are doing nothing with Social Security. They are leaving it the way it is. They want to increase it.”
Trump later said, “So far, I cannot believe how civil it's been up here.”
ON TRUMP’S SAYING ‘ISLAM HATES US’
When asked by debate moderator Jake Tapper whether his comment that “Islam hates us” meant all 1.6 billion Muslims, Trump responded by saying, “I mean a lot of them. I mean a lot of them.”
He added, “Well, you know, I've been watching the debate today. And they're talking about radical Islamic terrorism or radical Islam. But, I will tell you there's something going on that maybe you don't know about, and maybe a lot of other people don't know about, but there's tremendous hatred. And I will stick with exactly what I said to Anderson Cooper.”
RUBIO: “Let me say, I know that a lot of people find appeal in the things Donald says because he says what people wish they could say. The problem is presidents can't just say anything they want. It has consequences here and around the world.”
Trump hit back, “Marco talks about consequences. Well, we've had a lot of consequences, including airplanes flying into the World Trade Center, the Pentagon and could have been the White House.”
“I don't want to be so politically correct,” Trump added. “I like to solve problems. We have a serious, serious problem of hate. There is tremendous hate. There is tremendous hate.”
“Politically correct,” Rubio replied. “I'm not interested in being politically correct. I'm interested in being correct.”
CRUZ: “The answer is not to yell, ‘China, bad, Muslim, bad.’ You have to understand the nature of the threats we're facing and how you deal with them.”
TRUMP: “We have to knock out ISIS. We have to knock the hell out of them.”
ON DIPLOMATIC TIES WITH CUBA
“I would love a relationship between Cuba and the United States to change, but it would require Cuba to change, at least its government,” Cuban-American Rubio said.
TRUMP: “I do agree something should take place. After 50 years, it’s enough time, folks.”
ON CLIMATE CHANGE
“Sure, the climate is changing and one of the reasons is because the climate has always been changing,” Rubio said. “A law that we can pass in Washington to change the weather, there's no such thing.”
ON VLADIMIR PUTIN
KASICH: “Mr. Putin, you better understand you're either with us or against us.”
TRUMP: “I think Putin has been a strong leader for Russia. He's been a lot stronger than our leader and that doesn't mean I'm endorsing Putin.”
The New York real estate mogul added, “I don't say that as a good way or bad way. I say it as a fact.”
ON TRUMP’S RALLIES
When asked to comment on video that surfaced of a protester being punched by a man attending a Trump rally Wednesday, Trump said, “I certainly do not condone that at all, Jake.”
Trump went on, “we have some protesters who are bad dudes, they have done bad things. They are swinging, they are really dangerous.”
Cruz fired back, saying, “The only hand raising I'm interested in doing is on January 20, 2017, raising my hand with the left hand on the bible.”
Trump said, “Everyone's laughing, we're all having a good time. That's why I have much bigger crowds than Ted, because we have a good time at mine.”
ON A CONTESTED CONVENTION
TRUMP: “First of all, I think I'm going to have the delegates, OK?
“There's two of us up here that can [have the delegates] and there are two of us that cannot, at this moment. By the way, that is not meant to be a criticism, that's just a mathematical fact, OK?
“I think that whoever gets the most delegates should win.”
“Make me president,” Trump said under his breath.
Cruz joked, “Donald, you are welcome to be president of the Smithsonian.”
ON TUESDAY’S PRIMARIES
RUBIO: “On Tuesday night, I didn't do as well, obviously, as I wanted to and I was a little bit disappointed,” the Florida senator admitted.
“My wife told me a story that night. There's a gentleman here in South Florida who just got out of surgery. His doctors told him he needs to be home resting. Every day, he sits outside of a polling center and holds a sign that says, ‘Marco Rubio.’”
ABC News’ Katherine Faulders contributed to this report.