Megyn Kelly was due to moderate the debate in Utah on Monday.
Monday's Republican debate in Utah has been canceled after Donald Trump said he won't be attending.
The GOP frontrunner was due to take on remaining rivals Senator Ted Cruz and Ohio Governor John Kasich at the debate moderated by Fox News' Megyn Kelly in Salt Lake City.
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But on Wednesday morning, Trump said he would not be appearing.
"I was very surprised when I heard that Fox called for a debate," Trump said during an interview on "Fox & Friends." "Nobody told me about it. I won't be there, no."
He said that he had already made a commitment to speak at the American Israel Public Affairs Committee Conference in Washington, D.C., and would not change his plans.
After Trump's comments, Kasich said he would be skipping the debate as well.
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"Donald Trump's decision to scuttle the Salt Lake City debate is disappointing," said John Weaver, Kasich's chief strategist. "We had hoped to contrast Governor Kasich's positive inclusive approach to problem solving with Trump's campaign of division. If he changes his mind, we will be there."
Cruz responded to Trump's decision on Twitter by calling him "Ducking Donald."
In a statement, Fox News EVP Michael Clemente explained: "On Feb. 20, the Republican National Committee announced that a GOP presidential primary debate would be held on March 21 in Salt Lake City. They offered that debate to Fox News Channel to host, provided there were enough candidates actively campaigning.
"This morning, Donald Trump announced he would not be participating in the debate. Shortly afterward, John Kasich's campaign announced that without Trump at the debate, Kasich would not participate. Ted Cruz has expressed a willingness to debate Trump or Kasich -- or both. But obviously, there needs to be more than one participant. So the Salt Lake City debate is cancelled."
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