Donald Trump, by refusing to participate in tonight's Republican presidential debate, has rewritten yet another chapter of the political playbook.

Most candidates wouldn't dream of skipping a nationally televised debate so close to the first test with voters in the Iowa caucuses on Monday. In this election in particular, with such a crowded field of candidates, any air time is good time.

But as he has shown time and again, Trump is not most candidates.

His feud with Fox News, simmering since the network's first debate in August, reached a boil this week when the network announced Megyn Kelly would reprise her role as moderator.

Trump, no fan of Kelly's since she asked him in that debate about insulting women, floated the idea of boycotting the debate unless Fox replaced her. She's a "total lightweight," a "third-rate" reporter who is "very biased" against him, Trump said.

He used social media to ask his supporters what he should do. While they were weighing in, Fox News released statements saying it was surprised Trump was "willing to show that much fear," and that Kelly is an excellent journalist who would "absolutely" be moderating the debate. One satirically written statement made fun of Trump for consulting his Twitter followers.

Megyn Kelly Donald Trump Fox News Aug 6 2015 Republican presidential debate

These Aug. 6, 2015 photos show Trump and Fox News moderator Megyn Kelly during the first Republican presidential debate. (John Minchillo/Associated Press)

Trump said in Iowa Tuesday night that the "wiseguy" statements prompted him to say "bye bye" to the debate, and his campaign put out a statement saying he would instead host a competing event for wounded veterans.

"They can't toy with me like they toy with everybody else. So let them have their debate, and let's see how they do with the ratings," he told reporters in Iowa.

Trump has taken many perilous steps along his campaign path, such as proposing to temporarily ban Muslims from entering the U.S., but this latest move is one that some observers are saying is especially risky.

"I think Trump's decision hurts him. Not to show up at a debate right on the eve of the election with so many undecided caucus goers is, I think, a mistake," David Yepsen, a former top political journalist at Iowa's Des Moines Register, said in an interview. Yepsen now heads the Paul Simon Public Policy Institute at Southern Illinois University.

Boycott could insult Iowa voters

Trump is leading the polls in Iowa and would have been the prime target for his rivals in the debate. Yepsen suggested Trump may not want to take the chance of jeopardizing his lead with a poor debate performance and that the feud with Kelly is really a smokescreen.

"He's going to try and sit on a lead. The flaw in that is that I think it offends people," said Yepsen.

While some Iowa voters may hold it against Trump, his supporters "just love it," according to Simon Conway, a conservative talk radio host in Des Moines. He was hosting a town hall Tuesday night when the Trump boycott news broke.

GOP 2016 Cruz

Ted Cruz is challenging Donald Trump for the lead in Iowa, where he campaigned on Monday. Cruz says Trump's decision to skip the debate is disrespectful. (Evan Vucci/Associated Press)

Conway doesn't think this will hurt Trump's chances of victory. "He's broken every single possible rule of how you're supposed to caucus, and they love it," Conway said in an interview.

"It feeds into that narrative that here is a leader who is going to tell us what he's going to do and then he's going to do it," he said.

Trump has nothing to gain from the debate anyway; the candidates who are struggling to catch up to him need the platform more than he does, Conway said.

They are the ones who could actually be helped by Trump's absence. Ted Cruz, Trump's main competitor in Iowa, said it shows a lack of respect for Iowa voters. He then challenged Trump to a head-to-head debate. Trump has not yet responded.

Trump's absence tonight as the centre of attention will give the other candidates "some breathing space to make their case," said Yepsen.

For the undecided voters and for those who know they don't like Trump but don't know yet who they do like, tonight's debate will be important.

Fox defends Kelly

John Zogby, a political commentator and pollster, said it's hard to predict whether Trump skipping the debate will help or hurt his campaign.

"Conventional wisdom would suggest he hurts himself," said Zogby, but, Trump has broken every rule so far and still keeps coming out on top. "Either Trump rules on this one or convention does. If Trump rules, his numbers will go up again."

Trump has lambasted plenty of reporters before, but picking a battle with Fox News, a conservative ally, and one of its top personalities is also seen as risky.

"He has insulted a very popular reporter and a very powerful conservative voice," said Zogby. Could Trump's attitude toward Kelly hurt his chances with women voters?

"It's supposed to," said Zogby. But again, there's no telling when it comes to Trump.

Yepsen said Trump's claim that Kelly is biased doesn't ring true with everyone.

"I think he runs the risk of picking a fight with the wrong person. Fox News has a lot of credibility with American conservatives," he said.

Fox News is standing firmly behind Kelly and said Trump has "viciously attacked" her since the August debate. Trump slammed her after the event, insisting she treated him unfairly and she was out to get him.

"There was blood coming out of her eyes, blood coming out of her wherever," he said in one interview. Contrary to how many interpreted that comment, Trump said he was referring not to her menstrual cycle, but to her nose.

Trump avoided Fox for a while, its president Roger Ailes tried to smooth things over, and they resumed their mutually beneficial relationship. 

He's still welcome to join the debate tonight, the network says, and as Kelly said on her show Tuesday night, "The debate will go on, with or without Mr. Trump."