Republican presidential hopeful Donald Trump refused to back any nominee but himself, another flip-flop in his position since the start of the race.

In an interview on CNN, the party frontrunner was asked if he would support the Republican candidate for the White House, no matter who it ends up being.

"No, I don't anymore," Trump said. "No, we'll see who it is."

Trump added: "I have been treated very unfairly. By basically the RNC (Republican National Committee), the Republican party, the establishment.

"I'll see who it is. I'm not looking to hurt anybody. I love the Republican party."

Trump said he would win the nomination in any case, and that he did not need an endorsement from his main rival, Texas Senator Ted Cruz.

Cruz has recently been ambiguous over whether he would endorse Trump if he himself does not win the party nomination.

Relations between the two hit a new low after a week of backbiting, including a Twitter exchange of photos of Trump's wife Melania, a retired model, and a seemingly unflattering photo of Cruz's wife, Heidi.

The campaign for the primaries got off with a bang in August when Trump declined to say he would support whomever the party nominated and refused to rule out running as a third party candidate.

In September, however, Trump agreed to a sort of oath with the Republican Party. But in February he declared himself freed of it, saying the party had treated him poorly.

In a debate on March 3, he changed his mind again and promised to honor the oath with the party.

Source: AFP