It was late March, and Donald Trump was preoccupied with the swirl of new investigations launched by House Democrats against him and his inner sanctum, and with the coming delivery of Special Counsel Robert Mueller’s long-awaited report on Russian election meddling and Trump’s possible obstruction of justice.

In the midst of all this, there was another question weighing heavily on the president’s mind: Was Fox News, his favorite organ of conservative media and pro-Trump messaging, being sufficiently subservient to him?

“Keep an eye on it,” Trump started telling aides, according to two people with direct knowledge of his directive, in conversations about what was going on behind-the-scenes at Fox, and if there was any cause for concern for even the slightest positive coverage of any Democrat.

To any casual observer of Fox News or the Fox Business Network, this might seem like a hilariously irrational fear. The networks’ ratings-driving primetime lineups are jam-packed with vociferous Trump defenders, and some of Fox’s biggest names—such as Pete Hegseth, Sean Hannity, Lou Dobbs, Rupert Murdoch, to name just a few—have long served as sounding boards, phone-a-friends, and informal advisors to the president.

But privately, President Trump had been raising these questions of institutional loyalty, on-and-off, since at least the middle of last year. Several people who’ve heard him do this view it as more of a gutcheck than a loss of faith, and as yet another indication that Trump can interpret even the smallest deviations as a slight or a betrayal.

His suspicions were once again piqued one Sunday morning last month, shortly following the suspension of Fox host Jeanine Pirro, a Trump friend and loyalist.

“Keep fighting for Tucker [Carlson], and fight hard for @JudgeJeanine,” the president wrote on Twitter on March 17. “Your competitors are jealous - they all want what you’ve got - NUMBER ONE. Don’t hand it to them on a silver platter. They can’t beat you, you can only beat yourselves!”

At the time, Media Matters had been releasing unearthed audio clips of Carlson making various repulsive comments, such as defending statutory rape and calling Iraqis “semiliterate primitive monkeys,” and Pirro was briefly suspended by Fox for anti-Muslim comments regarding Rep. Ilhan Omar (D-MN).

A few hours after he posted that tweet, however, the president was back online, lashing out at a different corner of Fox News. “Were @FoxNews weekend anchors, @ArthelNeville and @LelandVittert, trained by CNN prior to their ratings collapse?” he tweeted that Sunday. “In any event, that’s where they should be working, along with their lowest rated anchor, Shepard Smith!”

It was around the time of this tweet that the president began telling those close to him to monitor the channel, to “keep an eye” out for hints of dissension in the ranks, and to report back to him on anything troubling. The White House did not immediately respond to requests for comment on this story.

To those who’ve worked for Trump, such behavior isn’t all that surprising.

During the early days of his 2016 presidential run, recalled Sam Nunberg, a former political adviser to Trump who worked on the beginning of the campaign, Trump privately and repeatedly complained about several Fox personalities he believed had crossed him, including Dana Perino, former host Megyn Kelly (even before their public tiff started by her questions during a Republican primary debate), and Fox Business Network star Neil Cavuto.

He felt especially aggrieved and kept mental note of the Fox on-air talent he felt had been dismissive of his run for office. Trump would often use the same five words when expressing his disappointment to a host from the otherwise friendly network: “ I’m very surprised by you .”

Nunberg recounted being in the future president’s Trump Tower office in May 2015—a month before the campaign’s launch—while Trump was on the phone for an interview with Cavuto. By the conclusion of their on-air chat, the businessman-turned-politician felt Cavuto wasn’t taking his presidential ambitions seriously and spent too much time badgering him about his finances. This was, to Nunberg’s recollection, the “start of Trump despising Neil.”

After Trump hung up the phone, he looked up at his aides assembled in his office and said, “What the hell was that? We’re not doing him again,” according to Trump’s former adviser. “Yeah, why was he being such an asshole?” Nunberg recalled replying to his boss at the time.

Of course, the president couldn’t fully enforce that grudge, as Cavuto co-hosted the Fox Business Network’s Nov. 2015 Republican primary debate. And Trump even sat down for a cordial one-on-one with Cavuto immediately following that event, during which the future president complimented Cavuto, saying, “You did a really elegant job” and “great job.”

“When I was [on the campaign], part of our strategy was to go around Fox News,” Nunberg told The Daily Beast on Wednesday. “The president wanted to get all the coverage he could possibly get and saturate media… That was something I talked to Trump about early on in the campaign. The president decided that we weren’t going to run in the Fox News primary or by their rules.”

He continued: “We didn’t think Fox News was out to get him, but we didn’t think they were going to prefer Donald Trump to be the nominee at that point, especially when you had people like Karl Rove and Dana Perino on the station. Eventually, Fox News was going to have to make a business and political decision to come around to him. That was something that the president discussed with me [during the primary].”

But in the years since, and even after becoming president, Trump has not stopped keeping tabs on who at Fox is, or isn’t, remaining faithful to him and his cause. This week, Trump kicked up some more dust, seemingly referring to himself and Fox News as “we.”

“So weird to watch Crazy Bernie on @FoxNews. Not surprisingly, @BretBaier and the ‘audience’ was so smiley and nice. Very strange, and now we have @donnabrazile?” the president tweeted on Tuesday, the morning after 2020 Democratic presidential contender and democratic socialist Bernie Sanders appeared at a Fox-hosted town hall event.

By Tuesday evening, the subject still clearly bothered Trump.

“Many Trump Fans & Signs were outside of the @FoxNews Studio last night in the now thriving (Thank you President Trump) Bethlehem, Pennsylvania, for the interview with Crazy Bernie Sanders,” the president posted to Twitter, making a baseless claim about his “Fans” being shut out. “Big complaints about not being let in-stuffed with Bernie supporters.”

Trump concluded his tweet with a rhetorical question: “What’s with @FoxNews?”