Des Moines, Iowa (CNN) For nearly two decades, Republican presidential candidates have run with Fox News. Now, Donald Trump is betting that he can run against it.

Trump's six-month war with host Megyn Kelly, which turned nuclear when he pledged to skip the Fox News debate that she is co-moderating on Thursday, has exposed a significant shift in the political-media landscape: The growing divide between ultraconservatives and Roger Ailes' Manhattan-based network.

Trump's attacks on the network -- like those he's made on Mexicans Muslims , Sen. John McCain , and others -- are no random acts of emotion, conservative pundits and campaign strategists told CNN. Instead, they indicate calculated tactical moves designed to stoke support among a conservative base that no longer worships Fox News as it once did.

In 2016, that conservative base is coming to believe that Fox News is more in line with the increasingly despised Republican establishment than with the ultraconservatives who support insurgent candidates like Trump and Ted Cruz.

"Most of my audience has a bipolar feeling about Fox News," Steve Deace, the conservative Iowa radio host who is backing Ted Cruz, said during an interview with CNN. "They view it as the most reliable place to go for news coverage, but they have grown increasingly untrusting of it when it comes to analysis."

For Deace, Trump's supporters are ultimately "desperate people" who "will latch onto megalomaniacs who claim to have all the answers." But as a proxy for conservative sentiment in Iowa and beyond, Deace is also well aware of his constituency's dissatisfaction with the cable news network.

"I saw this beginning in 2008, I saw a lot more of it in 2012, I see even more of it now," Deace continued. "Their feeling is that most of the Bush establishment people they put on there -- from Brit Hume to [Charles] Krauthammer to Karl Rove -- have been in the tank all along for anybody other than Trump and Cruz."

Fox News declined to comment for this story. Despite its reputation as a right-wing media network, it has long endured attacks from those who believe it is not conservative enough, although now that fault-line is being exposed in a dramatic way.

Hard-right conservatives still have a few heroes on Fox News, including Sean Hannity and Eric Bolling. But for many, the familiar stable of contributors is starkly at odds with their worldview.

Hume has suggested that Trump's star will fade because he is a former Democrat. Krauthammer has questioned Trump's temperament and political philosophy. Rove has said that Trump's nomination will cost the GOP the White House. George Will, whom Trump has sparred with publicly, went even further and stated that Trump's nomination would bring about the end of the party.

Many conservatives also don't find the prime-time hosts other than Hannity to be sufficiently to the right. Bill O'Reilly has avoided the conservative label and been one of Trump's toughest interviewers, while journalists like Kelly and Greta Van Susteren have eschewed any partisan loyalty and covered the Republican candidates through a skeptical lens.

That rift has enabled Trump to wage war against the very network that has historically been one of the most influential players in the Republican primary contest.

For any other candidate, taking on the Fox News juggernaut would amount to political suicide. But not so for Trump, a reality television star and international celebrity who commands record audiences, regardless of what network he appears on.

While Fox News may be the cable news ratings leader, that is only a relative victory: The network's most popular shows still average fewer than 3 million viewers each night, the vast majority of whom are over the age of 65.

"Fox has a few million viewers over 65. 'The Apprentice' had four to five times that audience," John Podhoretz, the editor of Commentary magazine and a columnist for The New York Post, explained, referring to Trump's former NBC reality show.

"Fox kills everybody in the cable news ratings, but their primetime viewership is like 4 percent of the people who voted in the 2012 election. The average O'Reilly viewer is, like, 70," said Deace. "The average Iowa caucus goer is not the average Fox viewer."

Further evidence of the split could be seen in the hours after Trump's announcement, when hardline conservative pundits rallied behind Trump -- not Fox News.

On Twitter, Ann Coulter encouraged Ben Carson to "skip the boring debate and do the wounded warriors event with Trump!"

Rush Limbaugh, the king of talk radio, praised Trump's decision and accused Fox News of "acting as if they had been jilted at the altar."

Limbaugh then lumped Fox News in with the rest of "the media" -- a loaded term that carries negative connotations in conservative circles.

"The media run this game," Limbaugh said. "The media in their minds and the way everybody plays the game, you have to go through the media to get where you want to go if you are in politics. You have to, and you have to bite your lip along the way. And if you don't, then you have made a perpetual enemy of people, as goes the saying, who buy ink by the barrel."

And the conservative thinker William Bennett said in a statement, "Of course Donald Trump can be a difficult character; he needles and provokes. But that does not give Fox News, or any network for that matter, leave to depart from its necessary posture of impartiality or, if you will, being 'fair and balanced.'"

For his part, Trump insists the reason he is boycotting the Fox News debate is Kelly and the last straw -- what he viewed as an insulting press release about him issued by the network.

"I don't like her. She doesn't treat me fairly. I'm not a big fan of hers at all," Trump said earlier this week. The next day, he posted an Instagram video in which he declared: "Megyn Kelly's really biased against me. She knows that, I know that, everybody knows that."

Fox issued a statement saying in part about Trump, "We can't give in to terrorizations of any of our employees."

And on Wednesday night, Trump tweeted a one-two punch: "It was the childishly written & taunting PR statement by Fox that made me not do the debate, more so than lightweight reporter, @megynkelly."