In several television interviews, Priebus, who chairs the Republican National Committee, said candidates sometimes make such statements in hopes of gaining leverage over the party, but that it would not work.

“Those kinds of comments, I think, have consequences,” Priebus said on ABC’s This Week. “And so when you make those kinds of comments and you want people to fall in line for you, it makes it more difficult.

“… And certainly, you know, if you were running for president of the Kiwanis Club or the Boy Scouts and you said you don’t know if you like the Kiwanis or the Boy Scouts, I think that makes your challenge even greater to ultimately win those kinds of posts,” he said. “It’s no different for the Republican Party.”

Donald Trump Blew Up the Republican Party’s Post-2012 Gameplan

On Tuesday, Trump backed away from the loyalty pledge he signed in September promising to support the party’s eventual nominee and not to run an independent campaign for the White House.

The RNC pledge has unraveled as Trump’s remaining rivals, U.S. Senator Ted Cruz of Texas and Ohio Governor John Kasich, also indicated they were unlikely to observe the pledge if Trump was the nominee.

Priebus said candidates signed the loyalty pledge as part of a deal in which the RNC agreed to provide data about voters. “We expect that when candidates make commitments, that they keep them,” Priebus told Fox News Sunday.

Trump’s relationship with the RNC has been contentious at times. Talking to Fox News Sunday, he once again did not rule out running as an independent if he does not get the Republican nomination.

“We’re going to have to see how I was treated,” Trump said. “I want to be treated fair.”

Priebus said that if one candidate gets the support of 1,237 delegates before the Republican convention opens in Cleveland in July, that candidate will win the party’s presidential nomination.

But if no one wins on the first ballot, delegates can switch their allegiances and “they can vote for who they want,” Priebus told ABC.

Nonetheless, Priebus told CNN, the nominee is likely to be one of the three people now running and not someone like House of Representatives Speaker Paul Ryan, who some have speculated could be a dark-horse candidate—mainly because “he doesn’t want to do it.”

Priebus also cited some practical reasons that the nominee most likely would have to be Trump, Cruz or Kasich: “That candidate would have to have a floor operation (in Cleveland) and an actual campaign going on to make that possible.”