Republican presidential candidate, Sen. Marco Rubio, R-Fla., left, speaks as Republican presidential candidates, businessman Donald Trump and Republican presidential candidate, Sen. Ted Cruz, R-Texas,  listen, during the Republican presidential debate sponsored by CNN, Salem Media Group and the Washington Times at the University of Miami,  Thursday, March 10, 2016, in Coral Gables, Fla. (AP Photo/Wilfredo Lee) Republican presidential candidate, Sen. Marco Rubio, R-Fla., left, speaks as Republican presidential candidates, businessman Donald Trump and Republican presidential candidate, Sen. Ted Cruz, R-Texas, listen, during the Republican presidential debate sponsored by CNN, Salem Media Group and the Washington Times at the University of Miami, Thursday, March 10, 2016, in Coral Gables, Fla. - AP 

MIAMI: Republican White House hopefuls ditched the insults and heated rhetoric that have come to define the 2016 race on Thursday, talking policy and substance on the debate stage in a stunning show of civility. Donald Trump and his challengers for the party's nomination have traded weeks of often below-the-belt barbs, and the anticipation for the debate in Miami had felt more like the run up to a heavyweight championship bout.

Four men took to the stage in Miami: Trump, Texas Senator Ted Cruz, Ohio Governor John Kasich and Senator Marco Rubio of Florida, who needs to pull off an upset win when his home state votes next Tuesday if he is to salvage his struggling campaign. Not a voice was raised in anger as the candidates sparred in measured tones, without interrupting, on immigration and visas, trade tariffs, Cuba policy, climate change and what to do to reduce the terror threat.

"We're all in this together. We're going to come up with solutions. We're going to find the answers to things," said Trump at one point, as he tackled immigration and security challenges. "And so far I cannot believe how civil it's been up here," marvelled the billionaire frontrunner, who has been working hard to appear more presidential looking ahead to a possible general election showdown with Democratic frontrunner Hillary Clinton. Floridians vote on March 15 along with residents of Ohio and Illinois. All three big states are winner-take-all in the Republican delegate race, the first such contests in the 2016 cycle.

Rubio on the ropes

Many in the party see next Tuesday's votes as the last best chance to derail the billionaire real estate mogul's insurgent candidacy. Trump is by all accounts the man to beat. He emerged strengthened by victories Tuesday in Michigan, Mississippi and Hawaii, and has now won 15 of 24 races. And he has boldly predicted he will win Rubio's Florida and Kasich's Ohio, which would in all likelihood put the final nail in the coffin for their campaigns.

Trump leads Rubio in Florida by a dramatic 43 to 20 percent among likely Republican primary voters, according to a Fox News poll released Wednesday, while Kasich leads in his own state with 34 percent support.

Trump caused a global firestorm in December when he called for a ban on Muslims entering the United States, and on the eve of the debate he unleashed a stunning new provocation, telling CNN: "I think Islam hates us." Despite the debate's civility, Trump doubled down on the sentiment Thursday. "I will stick with exactly what I said."

Rubio leaned in for criticism. "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," he said. Rubio denied Trump's suggestion he was afraid of speaking tough truths for fear of causing offense. "I'm not interested in being politically correct. I'm interested in being correct," he shot back.

Rubio was championed by party luminaries as the best mainstream hope of derailing Trump, but he has performed dreadfully in several recent primary contests, including those on Tuesday. With his campaign on the verge of fizzling, Rubio has stressed it is crucial to gang up on the frontrunner and has called on all Republicans to get behind him as the only candidate with a chance to beat him in Florida. Rubio was far more polished and serious on stage Thursday than in recent weeks and debates, when his strategy appeared to be to deliver Trump a dose of his own belligerent medicine.

'Bad dudes'

He had ripped into Trump's looks, belittled his small hands, even suggested Trump had wet his pants. But the strategy backfired: after votes were counted in Michigan, Mississippi, Idaho and Hawaii on Tuesday, Rubio walked away with zero delegates. Instead, Rubio offered coherent policy platforms, including on Social Security, saying changes would have to be made including raising the retirement age or risk a US "debt crisis."

Cruz, who has emerged as the most viable anti-Trump candidate, is aiming to spoil any Rubio resurgence, campaigning heavily in Florida in the run up to the primary. Cruz did clash with Trump several times, notably over his incendiary call for the US military to target the families of terror suspects and trade tariffs.

"We've never targeted innocent civilians and we're not going to start now," Cruz said. The real estate mogul has said he would threaten countries like China and Mexico with import tariffs as high as 45 percent if they did not play by international trade rules, but Cruz said that would only hurt the pocketbooks of hard-working Americans. "We've got to get beyond the rhetoric of 'China bad' and actually get to how do you solve the problem."

Trump also addressed the issue of violence at his rallies, following the arrest of a man who punched a protester in the face in a chaotic scene at one of his campaign events. "I certainly do not condone that at all," Trump said. But he added: "We have some protesters who are bad dudes, they have done bad things." - AFP