Here's a quick recap:
* The debate is the last before Tuesday's five high-stakes state primary contests, including winner-takes-all Florida and Ohio. The Northern Mariana Islands will also hold its caucus.
* The four Republican candidates stuck mostly to pitching their own policies rather than flinging the sort of personal attacks that have become the norm in recent weeks.
* The expectation that frontrunner Donald Trump would be ganged up on did not materialize, for the most part, with differences largely staying within policy, not personal, lines.
* Senators Ted Cruz and Marco Rubio did spar with Trump on who, as the two leading candidates, would be best suited to defeat Hillary Clinton in the general election.
The Republican presidential debate on Thursday saw a major shift among the four remaining candidates, who instead of flinging insults kept mostly to highlighting each other’s policy differences.
The change from the name-calling and body part references came just days ahead the high-stakes primary contests on Tuesday. Five states — North Carolina, Missouri, Illinois, Ohio, and Florida — will be up for grabs, as well as the Northern Mariana Islands caucus.
For Florida Sen. Marco Rubio, who has yet to win single state, a loss in his home state would be widely seen as the death knell to his campaign. He sought to frame his candidacy as the right one for the next generation, but as the night wore on, it became clear that frontrunner Donald Trump and No. 2 rival Texas Sen. Ted Cruz see the primary as a two-way race.
"I think, frankly, the Republican establishment — or whatever you want to call it — should embrace whats happening," he said. "We're going to beat Hillary, or whoever it may be, and we're going to beat them soundly."
Here's a look at some of the more significant exchanges during the roughly two-hour debate:
On immigration reform and guest worker visas, the candidates all agreed that the current system was broken and full of loopholes.
Trump brushed off criticism that his campaign promises are inconsistent with how he has acted in the private sector, saying, "No one knows the system better than me."
The real estate mogul said that he took advantage of the laws on the books while he was a private citizen, but he will change it as president.
"I'm the one who knows how to fix it," he said. "Nobody else on this [stage] knows how to change it like I do, believe me."
When asked on his trade policies, Cruz said his main focus will be protecting American workers and ensuring that jobs stay in the U.S.
"We're getting killed in international trade right now," he said. "And we're getting because we have an administration that doesn't look out for American workers."
As for Rubio, he said he supports free trade deals as long as they are good for all Americans.
He said the U.S. is getting killed through high tariffs overseas.
"I'm in favor of deals that allow us to bring down those tariffs," he said.
Kasich chose to focus on his blue-collar roots when asked about trade, saying he can empathize with the average worker.
"I will absolutely blow the whistle and stand up for the American worker," he said.
And how about that wall?
Trump's controversial pitch of building a wall along the U.S.-Mexico border got some love on stage from Kasich and Cruz.
"I would say we have to absolutely finish the wall and guard the border," Kasich said.
Cruz also reiterated his hard-line stance on immigration.
"We're going to build a wall, triple the border patrol, we're going to end sanctuary cities," he said, adding, "We're going to cut off taxpayer funds to any city that denies federal immigration law."
Trump also confirmed the upcoming endorsement of former rival Ben Carson:
Carson, who ended his presidential campaign last week, said on Thursday that he's "certainly leaning" toward endorsing Donald Trump for president.
"Let's put it this way, I'm certainly leaning," he said.
Multiple outlets, citing unnamed sources, later confirmed his Trump endorsement.
On the political hot potato that is Social Security, the candidates differed slightly on how to keep it solvent.
Both Rubio and Cruz dismissed Trump's plan to save Social Security by cutting waste, with the Texas senator calling it "fanciful."
Trump said that if elected he wouldn't change Social Security, but would instead focus on cutting waste in other areas of the budget.
He said after he successfully did so the U.S. "will save a fortune."
"I want to make our country rich again so we can afford it," he said.
But Cruz called Trump's vision unspecific, and said Social Security's fate couldn't ride on "some fanciful waste, fraud, and abuse."
Cruz said he advocates "gradually" raising the retirement age, and allowing younger people to have control over their social security like a 401K.
"We need to see political courage to take this on and strengthen and save Social Security," he said.
Rubio also advocated raising the retirement age to save the program, saying it would be gradual and wouldn't affect people close to retirement.
"I am against any Social Security changes that are bad for my mother," he said.
Trump also doubled down on his recent comments regarding Muslims hating the U.S.
When asked by Jake Tapper if he meant all 1.6 billion Muslims around the world in an interview with CNN's Anderson Cooper, the candidate said, "I mean a lot of them."
Trump went on to say he doesn't care about being politically correct when it comes to Islamic terrorism, prompting a fiery response from Rubio.
"I'm not interested in being politically correct, I am interested in being correct," he retorted.
The real estate mogul said Americans should change our laws to be on somewhat of an "equal footing" with ISIS.
"We need to expand our laws or we are being a bunch of suckers and they are laughing at us," he said.
Trump also said he supports a large troop deployment to "knock out ISIS."
"We really have no choice. We have to knock out ISIS - knock the hell out of them."
When challenged to give a number of troops, Trump said he'd listen to generals, but said he'd been hearing "20 to 30,000."
He went on to say that after a swift victory, American troops would quickly return and the U.S. get back to rebuilding itself.
Cruz and Rubio took Trump to task on the warming of relations between the U.S. and Cuba.
Rubio harshly criticized the restoration of diplomatic relations with Cuba, saying "the only thing that's changed as a result of this opening is now the Cuban government has more sources of money with which to build their repressive apparatus."
He also sought to highlight how his position differed from that of Trump, who suggested that "something should take place" in the U.S. relationship with Cuba after a half-century of isolation.
Cruz, on the other hand, said he would reverse the current course and break off diplomatic relations with Cuba, saying "we shouldn't be allowing billions of dollars to go to nations that hate us."
Kasich also acknowledged that humans contribute to climate change.
When asked about climate change, Rubio said he is in favor of a clean environment, but that America cannot fix it through legislation currently on the table.
"As far as a law we can pass in Washington to change the weather, there's no such thing," he said.
He also passed off climate change as a historical constant.
Kasich, however, was more straightforward, telling the moderators: "I do believe we contribute to climate change."
But he added that he doesn't think laws to fight climate change and having a healthy economy are mutually exclusive.
But in the end, will the field fall in line behind the candidate with the most delegates?
As the GOP considers the possibility of a brokered convention, CNN's Tapper asked the candidates whether they thought the rival with the most votes should be the nominee even if they don't reach the needed threshold but still have the majority.
"I think whoever gets the most delegates should win," Trump said.
And his closest rival, Cruz, said he was adamantly against the GOP establishment "parachuting" a "Washington" candidate into the convention.
"That would be an absolute disaster and we need to respect the will of the voter," he said.
He did, however, follow that up with an impassioned case for him being the best candidate to beat Clinton.