Donald Trump's campaign manager says Trump skipping Thursday's GOP debate

Donald Trump will "definitely" skip Thursday's GOP debate due to a deepening fight with the Fox News Channel, according to his campaign manager Corey Lewandowski.

"It's not under negotiation," Lewandowski told reporters Tuesday evening.

Instead of attending the debate, "We'll have an event here in Iowa, with potentially another network, to raise money for wounded warriors," he said. "And Fox will go from probably having 24 million viewers to about 2 million."

Lewandowski ruled out Trump's participation just a few minutes after Trump himself said he would "most likely" hold a competing event in Iowa during the debate.

"Let's see how much money Fox is going to make on the debate without me, okay?" Trump said, asserting that the ratings will sink if he's not there.

Trump said he was outraged by a "wiseguy" Fox press release that mocked him earlier in the day.

Now Fox News and Trump are at loggerheads. Political observers immediately wondered whether Trump was bluffing. Media analysts asked whether Fox would leave an empty podium at center stage during Thursday's event, which is the last GOP debate before the all-important Iowa caucuses.

Fox had no immediate response to Trump.

The fracas escalated quickly Tuesday, but was the culmination of months of tension between the GOP frontrunner and the Fox News host Megyn Kelly.

Kelly challenged Trump during Fox's first debate back in August and will be back in one of the moderator chairs on Thursday. Trump says she is biased and shouldn't be allowed to moderate. Fox rejects that; on Monday the network said Trump is just "fearful" of the TV host.

The disagreement came to a head on Tuesday afternoon. Around 1 p.m. Trump polled his fans on Twitter, asking, "Should I do the GOP debate?"

The poll suggested a real reluctance to attend, perhaps because Trump, as the frontrunner, arguably has the most to lose on Thursday night. The respondents were evenly split, with about half saying he should skip it.

In an Instagram video that coincided with his poll, Trump said, "Megyn Kelly's really biased against me. She knows that, I know that, everybody knows that. Do you really think she can be fair at a debate?"

Fox interpreted his video as a serious escalation in an ongoing war of words.

An hour later, a network spokesperson issued a tongue-in-cheek statement imagining Trump conducting Twitter polls in the Oval Office.

"We learned from a secret back channel that the Ayatollah and Putin both intend to treat Donald Trump unfairly when they meet with him if he becomes president — a nefarious source tells us that Trump has his own secret plan to replace the Cabinet with his Twitter followers to see if he should even go to those meetings," the statement said.

The intended message to Trump was clear: "Grow up."

When Trump read the statement, he shot back with a tweet, calling it a "pathetic attempt by Fox News to try and build up ratings for the #GOPDebate."

He added, "Without me they'd have no ratings!"

At 6 p.m., Fox announced the lineup for Thursday's debate, with Trump at center stage. At a press conference 20 minutes later, Trump said he "probably" wouldn't show up.

One thing is for sure: Kelly will be there.

In a separate statement on Tuesday afternoon, Fox News chairman Roger Ailes said the "entire network stands behind Kelly" and that she "will absolutely be on the debate stage on Thursday night."

Kelly has stayed mum about the brouhaha.