Thursday night's Republican presidential primary debate began without any fireworks – a first for the series of GOP matchups – as the four remaining candidates steered clear of attacking each other and even the Republican Party's chairman counseled unity and calm.

'So far I cannot believe how civil it's been up here!' Trump marveled during a calm, cool and collected exchange about illegal immigration.

For nearly an hour, no one spoke in the second person. No one turned to address another candidate. Every statement was delivered facing the audience.

Trump said after the debate via telephone that it was a conscious choice: 'I think it was time to have that kind of debate. I thought it was necessary. It was a good thing.'

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Texas Sen. Ted Cruz (right) said Trump (left) was guilty of 'funding liberal Democrats, and funding the Washington establishment'

The Republican presidential candidates, from left, Marco Rubio, Donald Trump, Ted Cruz and John Kasich stand for a moment of silence for former first lady Nancy Reagan

'I was prepared to have to go the other way,' the pugnacious Republican said.

'If you hit me, I have to do it, punch back. it's a natural reflex.'

But ultimately he explained that 'I really wanted to see if we could all – and this isn't just me, it was the Republican Party – we wanted to see if we could have a strong, substantive debate.'

Texas Sen. Ted Cruz said Thursday night that Trump was guilty of 'funding liberal Democrats, and funding the Washington establishment,' and said the real estate tycoon couldn't be trusted to take on the federal government.

But he did it without raising his voice.

Republican National Committee chair Reince Priebus addressed the audience at the University of Miami before the debate began, using his time to calm the GOP's fraying nerves.

'This party is going to support the nominee, whoever that is, 100 per cent. There's no question about that,' he said.

Unspoken, but hanging heavy in the room, was the name of Donald Trump.

The billionaire front-runner has roiled the RNC with an unconventional slash-and-burn campaign style, trampling the party's more traditional candidates one by one since mid-2015.

Thursday night's Republican presidential primary debate in Miami began without any fireworks. Pictured from left, Marco Rubio, Donald Trump, Ted Cruz and John Kasich listen to the National Anthem

The billionaire front-runner has roiled the RNC with an unconventional slash-and-burn campaign style

The two 'establishment' candidates who remain – Florida Sen. Marco Rubio and Ohio Gov. John Kasich – are in third and fourth place among the quartet of candidates.

Republicans, Priebus insisted on Thursday night, 'are going to come together, unify in Cleveland, and get behind our nominee. That's what we do as Republicans.'

Cleveland will be the site of July's Republican national Convention.

'Any one of these four gentlemen would be a universe better than Hillary Clinton or a socialist like Bernie Sanders,' Priebus said.

Rubio, Florida's junior senator, received the night's largest ovation when he was introduced. But Trump set the tone for the night.

Trump (left) shakes hands with rival Ted Cruz as they arrive onstage at the CNN at the University of Miami

Marco Rubio (pictured), Florida's junior senator, received the night's largest ovation when he was introduced

'One of the biggest political events in the world is happening right now,' he said, noting that millions of Americans who usually don't participate in elections 'are voting out of enthusiam. They're voting out of love.'

Trump said that supporters of his, '50 years old, 60, years old, 70 years old,' tell him they will vote for him when they cast ballots for the first time.

'The Republican establishment, or whatever you want to call it, should embrace this,' he said. 'We're having millions of extra people join.'

'We're going to beat the Democrats. We're going to beat Hillary ... and we're going to beat them soundly.'

Trump also confirmed news that had been buzzing around Washington all afternoon, saying that he had met with Dr. Ben Carson, a former presidential candidate who dropped out last week.

He's 'endorsing me tomorrow morning,' Trump said.

'You can be politically correct if you want,' Trump said – finally breaking the taboo on talking directly to one of his opponents. 'I'm not interested in being politically correct,' Rubio countered

Trump said that supporters of his, '50 years old, 60, years old, 70 years old,' tell him they will vote for him

The evening's first disagreement – it would be an exaggeration to call it an argument, much less a fight – involved Trump and Cruz tussling gently on trade and tariffs.

Trump is 'right about the problem, but his solution doesn't work,' the Texan said, insisting that tariffs on China would only result in retail price increases.

'It's you that pays that tax,' he told Americans.

But Trump said 'it's just the opposite ... we will start building those factories, those plants here,' resulting in new jobs and a stronger economy.

Even the subject of radical Islam didn't bring out the fistfighting and brickbats.

Trump doubled down on his statement about Islam being at war with the United States.

'I mean a lot of them!' he said. 'There's tremendous hatred, and I'll stick with exactly what I said,'

Rubio charged that Trump 'says things they wish they could say. The problem is that a president can't just say whatever he wants' without bringing global consequences.

Trump never raised his voice in response, and never looked at Rubio.

'Marco talks about consequences. Well, we've had a lot of consequences including airplanes flying into the World Trade Center, and the Pentagon,' he said.

'You can be politically correct if you want,' Trump said – finally breaking the taboo on talking directly to one of his opponents.

'I'm not interested in being politically correct,' Rubio countered. 'I'm interested in being correct.'



