Fox News moderators Chris Wallace, Megyn Kelly and Brett Baier start Aug. 6 Republican presidential debate in Cleveland. (Aaron Josefczyk/Reuters)

They’ve called each other names. They’ve mocked, belittled, skewered and slimed.

And now that oddest of couples — Donald Trump and Fox News — is engaged in a tit-for-tat feud like none seen in the annals of modern American politics.

The greatest show on Earth — or at least in Iowa.

If things go as promised, Trump won’t be there Thursday when Fox hosts the final Republican debate before Monday’s Iowa presidential caucuses. He says he’s backing out because of a taunting statement from Fox, though his detractors accuse him of dodging a last showdown with his chief rival, Sen. Ted Cruz (Tex.). Instead, Trump has made plans to materialize elsewhere in Iowa, hosting a benefit for wounded veterans — counterprogramming on a Trumpian scale of swagger.

His threatened absence from the debate stage is a demonstration of Trump’s perception of his own self-worth, his verifiable status as a ratings-generating gargantuan whose screen persona can translate into millions of advertising dollars. In a sense, it’s an act of subversion by a candidate who has broken all the normal rules of modern campaigns. But it’s also a manifestation of Trump’s philosophy about getting what he wants when he wants it.

Republican Donald Trump is saying he "most likely" won't attend the debate Fox News anchor Megyn Kelly is set to co-moderate. Here's a look back at the clash that started with an earlier debate in August 2015. (Sarah Parnass/The Washington Post)

“The best thing you can do is deal from strength, and leverage is the biggest strength you can have,” Trump wrote in his career-
defining and profile-elevating 1987 bestseller, “Trump: The Art of the Deal.” “Leverage is having something the other guy wants.”

Fox, a network that has reigned as a kingmaker in Republican politics, now seems faced with an adversary who is acting as if he’s already the king and doesn’t need it.

The sniping peaked this week when the billionaire developer appeared to taunt Fox by polling his social media followers on whether he should appear at the debate. He also stepped up his attacks on Fox anchor Megyn Kelly, whom he wanted to have removed as debate moderator.

The poll and the Kelly criticism irked Fox News chairman and chief executive Roger Ailes, according to an executive at Fox, and the network chief personally crafted a statement in response: “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.”

According to the Fox executive, who spoke on the condition of anonymity to discuss private conversations, Ailes “put together a tongue-in-cheek statement to take the heat off Megyn.”

On Wednesday, Trump — via Twitter, naturally — said Fox went too far.

“It was the childishly written & taunting PR statement by Fox that made me not do the debate, more so than lightweight reporter, @megynkelly.”

While publicly feuding with Trump, the cable news behemoth also seemed to be at cross-
purposes with itself, toggling between the competing goals of taking a hard line with the recalcitrant candidate and wooing him.

Fox executives did not respond to multiple interview requests.

Trump and Fox have been poking at each other for months. Their needling and gnashing began face-to-face at the first Republican presidential debate in August, when Kelly pressed Trump about calling women “fat pigs” and other derogatory names. Trump parried back the next morning by huffing that Kelly had “blood coming out of her wherever.” Critics said that was a reference to the anchor’s menstrual cycle, but the candidate said it was merely a reference to her demeanor.

The tangle soon devolved into long-distance warfare, a series of snippy news conferences and social media taunts, periodically interrupted by detentes. Even as Trump has pounded away at Kelly, retweeting claims that she is a “bimbo” and calling her “average in everyway,” he has frequently appeared on Fox News programs.

A defiant Trump appeared on Fox host Bill O’Reilly’s show Wednesday night, his 133rd appearance on the network since announcing his presidential run, according to a Fox tally. When O’Reilly suggested that Trump was making a mistake by skipping the debate, the GOP front-runner said, “I think you’re wrong.”

Trump’s camp denied that the candidate was afraid to debate. “He loves debating. He has participated in six debates,” said Trump spokesman Corey Lewandowski. “He welcomes the opportunity to debate.”

Fox has claimed that the Trump spokesman leveled a threat against Kelly on Saturday in a conversation with one of the network’s executives. “Lewandowski stated that Megyn had a ‘rough couple of days after that last debate’ and he ‘would hate to have her go through that again,’ ” a Fox spokeswoman said in a statement. “We can’t give in to terrorizations toward any of our employees.”

When asked about the Fox claim, Lewandowski said: “I didn’t do anything of the sort. . . . I did not threaten anyone.”

Jill Olmsted, a journalism professor and media critic at American University, said the cable channel’s “unnecessarily snarky comments” mean that “Trump has won this round with Fox — big time.”

“They took the low road and made Mr. Trump look like he is being targeted by Fox,” she said. “I am quite surprised that grown-up media spokespersons for a major media outlet didn’t know better, or at least weren’t more practiced in holding their tempers when giving public comment.”

But John Carroll, a communications professor at Boston University, said: “This may be a situation where Donald Trump was too clever by half. It may have been a gambit to get concessions, but when Fox rightly told him to take a hike, he was boxed in. To save face he had almost no choice.”

Rush Limbaugh, the influential nationally syndicated radio host, concluded that Fox is underestimating Trump.

“I heard people on Fox last night talking about this. ‘Who does he think he is? He can’t control the media,’ ” Limbaugh said on his program Wednesday. “I got news for you: He is controlling the media, and it’s his objective . . . He controls the media when he’s not on it. He controls the media when he is on it. He controls the media when he’s asleep. Nobody else has been able to do anything like this short of the Kennedys, and they’re pikers compared to the way Trump is doing this.”

For the umpteenth time in this strange Republican primary season, Trump has made the race all about one thing: Trump.