Republican presidential hopeful Marco Rubio has attacked Donald Trump for saying that Islam hates America, in a televised debate in Miami, reports the BBC.
Mr Rubio, who faces a do-or-die contest in Florida on Tuesday, said Islam had a problem with radicalization but said many Muslims are 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," Mr Trump observed at one point.
But on the issue of Islam, there was clear distance between Mr Trump and the others-- all three of his rivals disagreed with him that the families of terrorists should be killed.