After Republican frontrunner Donald Trump announced that he will be boycotting Thursday's GOP debate in Iowa, many of the other presidential candidates spoke out, as did Fox News host Megyn Kelly, who will be moderating the debate, and Fox News Chairman and CEO Roger Ailes.

1. Sen. Ted Cruz (Texas)

Sen. Ted Cruz fired back in an interview on "The Mark Levin Show," challenging Trump to face off one-on-one.

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"If Donald is afraid of Megyn Kelly, I would like to invite him on your show to participate in a one-on-one debate between me and Donald, mano y mano," Cruz told the radio host, adding that Trump could pick the moderator.

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Cruz asserted that Trump's move "reflects a lack of respect for the men and women of Iowa, that he’s unwilling to go to Des Moines and be questioned" and contended that Trump's boycott signals that he is not qualified to be president. Cruz also said that Trump owes voters an explanation as to “how he is prepared to be commander-in-chief if he’s terrified of a television host," referring to Kelly, who asked Trump tough questions at the last Fox News debate.

“This is a job interview, you need to be willing to answer the questions of the American people, and if Donald is afraid to defend his record, that speaks volumes,” Cruz asserted. “And if he thinks Megyn Kelly is so scary, what exactly does he think he’d do with Vladimir Putin? I promise you Putin is a lot scarier than Megyn Kelly."

2. Gov. Chris Christie (N.J.)

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New Jersey Gov. Chris Christie expressed similar concerns, telling Kelly that Trump's refusal to "show up to battle" creates doubt about his leadership abilities and dedication to the American people.

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3. Former Florida Gov. Jeb Bush

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Jeb Bush echoed this sentiment, suggesting that Trump's fear of Kelly means he is not prepared or able to face formidable political opponents.

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4. Megyn Kelly, Fox News host and debate moderator

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Trump's decision to not participate in the debate is rumored to be due to the fact that Fox's Kelly will be one of the moderators. Kelly and Trump have had an ongoing feud, and the two have sparred at past debates. Kelly responded on air Tuesday night.

"The debate will go on with or without Mr. Trump," the host said on her show, "The Kelly File." She also tweeted a comment made by colleague Brit Hume:

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"This is [Trump's] first major misstep," political commentator Marc Thiessen told Kelly on her show, arguing that this debate boycott undermines Trump's platform of being "tougher than the other candidates." "Running from a fight is not a New York value," Thiessen said.

5. Roger Ailes, Fox News Chairman and CEO

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“Megyn Kelly is an excellent journalist and the entire network stands behind her — she will absolutely be on the debate stage on Thursday night,” Fox News Chairman and Chief Executive Roger Ailes announced in a statement to the Los Angeles Times.

According to multiple reports, Trump has refused to answer Ailes' calls and insists that he will only talk to News Corp Chairman Rupert Murdoch.