Donald Trump warned Republicans against plans to stir up dissent at the party's national convention in Cleveland next month, saying he would block anyone who hasn't endorsed him from getting a speaking slot.

"If there's no endorsement, then I not invite them to speak," the presumptive GOP nominee told The New York Times in an interview published Sunday.

The comments were pointedly aimed at two of his former rivals, Ohio Gov. John Kasich, who would normally be granted a speaking spot as the home-state host, and Sen. Ted Cruz of Texas, who won more than 500 delegates and enough states to be formally allowed to have his name entered into consideration, which by party rules would guarantee him time at the podium.

"You mean to tell me we're going to get the largest vote in the history of the Republican primaries, and now the same people that either didn't run or got beaten in a landslide are going to try and back-end?" Trump told the Times. "My supporters are tremendously loyal to me. They would not stand for it."

Trump's admonition comes as the faction of GOP members who oppose him is ramping up its efforts to prevent him from winning the nomination in Cleveland. While more than 1,500 delegates to the convention are bound by results of state primaries to cast their ballots for him in the nominating vote – he needs 1,237 to win – an effort is underway to change the rules to allow those delegates to vote their conscience.

Even in the wake of a bitter nominating contest, it would be highly unusual for those in Kasich's or Cruz's positions to turn down the opportunity to make a display of party unity – let alone be blocked from the spotlight by the nominee.

Kasich, who was the last man standing against Trump, despite winning just his home state, has so far refused to endorse him as the nominee. Earlier this month, the governor said he was under immense pressure to do so and still hoped Trump would morph into a candidate he felt comfortable supporting, but the list of reasons not to get on board was "getting bigger."

"Unless it changes, you know, I'm not going to be able to get there," he said. "It's trending all the wrong way."

A spokesman for Kasich declined to say if he had plans to speak.

Cruz, meanwhile, has said he plans to pitch a battle at the convention – but not necessarily for the nomination. After ending his campaign in early May, the tea party favorite vowed to defend conservative priorities in the party platform, particularly against efforts to soften language on abortion.

He has also so far refused to say if he will endorse or even vote for Trump.

But if both Kasich and Cruz have been cagey about their plans for Cleveland, others simply want no part.