Abandoning the nasty insults of past debates, Donald Trump and his Republican rivals turned Thursday night's presidential face-off into a mostly respectful but still pointed discussion of Social Security, Islam, trade and more. Trump shook his head and declared at one point: "I can't believe how civil it's been up here."
Ted Cruz and Marco Rubio didn't hesitate to lay out their differences with Trump, but the candidates largely managed to present those arguments without vitriol.
In a lengthy discussion of the threat posed by radicalized Muslims, Trump refused to back away from his recent statement that "Islam hates the West." He said he wouldn't stoop to being "politically correct" by avoiding such statements.
Rubio had a sharp comeback: "I'm not interested in being politically correct. I'm interested in being correct."
The Florida senator noted the Muslims in the U.S. military and buried in Arlington National Cemetery and said the only way to solve the problem of violent extremists is to work with people in the Muslim faith who are not radicals.
Cruz bundled together his criticisms of Trump for what he called simplistic solutions on trade and on Islamic terrorists, saying, "The answer is not to simply yell, 'China: bad, Muslim: bad.'"
Trump, though, clearly was intent on projecting a less bombastic - and more presidential - image.
His closing message: "Be smart and unify."
"We're all in this together," he said early on, sounding more like a conciliator than a provocateur as he strives to unify the party behind his candidacy. "We're going to come up with solutions. We're going to find the answer to things."
The candidates split down the middle - Trump and Texas Sen. Cruz vs. Florida Sen. Rubio and Ohio Gov. John Kasich - on the likelihood of the GOP race coming down to a brokered Republican convention this summer.
"I think I'm going to have the delegates, OK?" Trump said.
As for who has a realistic chance of winning the nomination, Trump simply wrote off Rubio and Kasich, saying, "There are two of us that can, and there are two of us that cannot, OK?"
Cruz heartily agreed with Trump on that.
Rubio countered that disappointing "delegate math" aside, he'd keep on fighting.
Kasich, for his part, said it wouldn't be so bad to have a contested convention. He added there are plenty of primaries left so "let's not get ahead of ourselves."
Trump's rivals, in a desperate scramble to halt his march to the nomination, gradually ramped up their criticism as the night wore on.
Rubio's overarching message: "I know that a lot of people find appeal in the things Donald says. The problem is presidents can't just say anything they want because it has consequences around the world."
Cruz, eager to cement his position as the party's last best alternative to Trump, had a string of criticisms of the GOP front-runner, too, saying flatly at one point: "His solutions don't work."
Trump refused to take the bait when Cruz repeatedly poked at his foreign policy positions and at one point lumped Trump with Hillary Clinton and John Kerry in supporting the Obama administration's Iran nuclear deal.
Trump's restrained response: "If Ted was listening, he would have heard me say something very similar" to what Cruz had said about the failings of the deal.
In a meaty discussion of Social Security, Cruz and Rubio both said they'd gradually raise the retirement age for younger workers to help stabilize the system and stave off financial disaster for the system.
Trump, in contrast, said he'd do "everything within my power not to touch Social Security, to leave it the way it is."
On that issue, the GOP front-runner couldn't resist taking a dig at the Democrats, saying he'd been watching them intensely -"even though it's a very, very boring thing to watch" - and that they weren't doing anything on Social Security.
Trump was questioned about whether he had set a tone at his rallies that fueled violent encounters between supporters and protesters.
"I truly hope not," he said, but added that many of his supporters have "anger that is unbelievable" about how the country is being run and that some of protesters were "bad dudes."
President Barack Obama, offering political commentary from the sidelines, said earlier in the day the party was going through a "Republican crackup" that had taken on the tone of a "circus." He blamed the GOP itself for fostering the idea "that cooperation or compromise somehow is a betrayal."
Florida is the biggest prize of Tuesday's five-state round of voting, and all 99 of the state's delegates will go to the winner.
In all, 367 Republican delegates will be at stake, with voting also occurring in Illinois, Missouri, North Carolina, Ohio and the Northern Mariana Islands.
In the race for delegates, Trump has 459, Cruz 360, Rubio 152 and Kasich 54. It takes 1,237 to win the Republican nomination for president.
Benac reported from Washington. AP Writers Donna Cassata and Laurie Kellman in Washington and Jill Colvin in Fayetteville, North Carolina, contributed to this report.