Donald Trump wins Kentucky caucuses

Republican presidential candidates Sen. Marco Rubio R-Fla. and businessman Donald Trump argue as Sen. Ted Cruz R-Texas and Ohio Gov. John Kasich listen during a Republican presidential primary debate at Fox Theatre Thursday

Then Mr Trump came in, denying it had been an issue before.

Texas Sen. Ted Cruz is trying to cast himself as the GOP's conservative savior as party insiders look for an alternative to Donald Trump, an irony considering his years spent fostering a reputation as an outsider willing to anger fellow Republicans as well as Democrats. Without directly addressing the suggestion, he said, "No doubt, if we remain divided, Trump wins". "That's very different. A lot of people that endorse me, I wouldn't endorse for president". Ted Cruz slammed the numerous checks he's written to boost Hillary Clinton's political career.

Trump said it was simply business.

The bad blood among the candidates flowed freely. "Nobody has ever hit my hands", Mr Trump said, referring to Mr Rubio's recent personal attack stating that the celebrity billionaire has small hands.

Cruz and others have suggested that in the session Trump might have been more flexible on immigration than in public statements insisting he would build a wall between the United States and Mexico and deport 11 million illegal immigrants.

Holding up both hands to the audience, the Republican said: "He (Rubio) referred to my hands, "if they're small, something else must be small".

"The time came when Trump's outrage made me have to speak out", he added, "because it comes to the point where your grandchildren are going to say, 'Poppa, what did you do to stop Donald Trump?'".

It was a jaw-dropping moment in a campaign that's been full of surprises from the beginning.

Trump had attacked Kelly on social media, and skipped another debate because Fox refused to remove Kelly as moderator. I have never heard of this. "You can't trust them", Rubio said. "If somebody tells them something, can they believe it?" When Cruz chimed in following Rubio's attack, Trump started to lose his cool, shouting, "It's a minor case!"

Offered Cruz, "Yes, because I gave my word that I would". Marco Rubio earlier in the week.

New York (CNN)What began as a Republican debate stage squabble - and ended as a two-man comedy routine - has taken on new life Friday as a fundraising tool.

The Detroit debate was one more opportunity for the Rubio and Cruz campaigns to try to slow Mr Trumps momentum. "He's trying to con people into giving him their vote just as he conned those people".