The next Republican presidential debate in Utah on Monday has been canceled after Donald Trump said he won't participate, the Republican National Committee confirmed to NBC News Wednesday.
Fox News would have hosted the debate in Salt Lake City.
The Republican presidential front-runner said he'd skip the event, and then John Kasich's camp said they'd pull out if Trump didn't participate.
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"Ted Cruz has expressed a willingness to debate Trump or Kasich -- or both," Fox News said in a statement. "But obviously, there needs to be more than one participant. So the Salt Lake City debate is cancelled."
An emboldened Trump offered himself Wednesday as the inevitable Republican presidential nominee and called on balky GOP leaders to embrace the voters' "tremendous fervor" for his candidacy. But the billionaire businessman's latest wins didn't stop anti-Trump Republicans from seeking scenarios to deny him the GOP nomination.
Trump, who padded his delegate lead in the latest round of voting, predicted he'd amass enough support to snag the nomination outright before the Republican convention — without much difficulty. And he served notice that if GOP leaders try to deny him the nomination at a contested convention when he is leading the delegate count, "You'd have riots."
With his latest wins, Trump has won 47 percent of delegates so far. He'll need to win 54 percent of remaining delegates to clinch the nomination before the convention, according to The Associated Press delegate count.
Despite Trump's momentum, some GOP leaders and conservatives continue to explore ways to block him.
Former House Speaker John Boehner waded into the fracas on Wednesday, saying he'd support his successor, Paul Ryan, for president if Republicans can't agree on a candidate at the convention.
Boehner, who has endorsed John Kasich, said that if Republicans can't nominate Trump, Kasich or Texas Sen. Ted Cruz on the first ballot, he'd be "for none of the above. I'm for Paul Ryan to be our nominee."
An aide to Ryan said later on Wednesday the speaker won't accept the nomination.
"The speaker is grateful for the support, but he is not interested. He will not accept a nomination and believes our nominee should be someone who ran this year," spokeswoman AshLee Strong said.
Democrat Hillary Clinton, eager for a November matchup against Trump, took direct aim at him after strengthening her position against rival Bernie Sanders with another batch of primary victories.
"Our commander-in-chief has to be able to defend our country, not embarrass it," Clinton said in a speech that largely ignored Sanders. "We can't lose what made America great in the first place."
Trump suggested in calls to morning TV shows that the party establishment is starting to fall in line behind him. Without naming names, Trump said some of the same Republican senators who are publicly running him down have called him privately to say they want to "become involved" in his campaign eventually. He picked up an endorsement Wednesday from Florida Gov. Rick Scott.
As for his expected Democratic opponent, Trump said Clinton would be "a major embarrassment for the country" and added that she "doesn't have the strength or the stamina to be president."
Kasich, celebrating his home state win over Trump, told NBC's "Today" show, "I dealt him a very, very big blow to being able to have the number of delegates."