Republican presidential hopeful Marco Rubio has attacked Donald Trump for saying that Islam hates America, in a televised debate in Miami.

Rubio, who faces a do-or-die contest in Florida on Tuesday, said Islam had a problem with radicalisation but said that many Muslims were proud Americans.

"Presidents can't just say whatever they want. It has consequences," he said, to cheers from the audience.

The four Republicans heeded pleas from party leaders to have a civil debate.

Unlike in the last TV event, which was littered with personal insults, this one was more substantive with a focus on policy.

"So far, I cannot believe how civil it's been up here," Trump observed at one point.

But on the issue of Islam, there was clear distance between Trump and the others. Trump stood by comments he made earlier in the day when he said "Islam hates us, there's a tremendous hatred", and railed against political correctness.

But Rubio said: "I'm not interested in being politically correct. I'm interested in being correct."

All three of Trump's rivals distanced themselves from Trump's statement in December that in the fight against terrorist "you have to take out their families".

"We've never targeted innocent civilians and we're not going to start now" Cruz said.

When Trump was challenged on the legality of targeting civilians, he said that America had to be able to fight on "an equal footing".

"We have to obey the laws, but we have to expand those laws", he said.

On Tuesday five large states will vote for presidential candidate in each party, with Ohio Governor John Kasich and Rubio, a Florida senator, under pressure to win their home states.

Trump picked up a key endorsement of Ben Carson, who last week dropped out of the race before the debate.

DEBATE HIGHLIGHTS:

Trump reaffirmed his opposition to H1-B visa programme, which allows US firms to employ highly skilled foreigners, saying "it's bad for our workers".

Rubio said he would delay retirement until 68 to help address the $150bn social security shortfall.

And he accused Trump's numbers of "not adding up" because he said he could save social security by eliminating waste.

Cruz said he was going to build a wall, triple the border control and end welfare benefits for undocumented.

Trump said he would "make education great" and that former Republican candidate Ben Carson would be involved.

And calling Vladimir Putin "strong" did not mean he was endorsing him as a good leader, said Trump.

Kasich disagreed with Mr Rubio, who said he did not believe in manmade climate change.

The candidates also clashed over President Barack Obama's historic visit to Cuba next week.

Rubio, whose parents were Cuban immigrants, said he was opposed to efforts to restore relations until Cuba improved its human rights record.

But Trump said he was not opposed to a US-Cuba deal, but it should be on better terms for the US.

The other Cuban-American candidate on the stage, Cruz, accused Trump of supporting the Obama-Clinton policy on Cuba.

Trump, a billionaire businessman from New York with no political experience, has dominated the news and the state primary contests so far.

On the Democratic side, Vermont Senator Bernie Sanders and former Secretary of State Hillary Clinton are battling for the party's nomination.

Clinton is leading Sanders in delegate counts so far, though his campaign has proved more formidable than expected.

Both parties will determine their nominees at conventions in July, then Americans will pick their new president in November.