“He’s a demonic force, a destroyer. But he’s not going to destroy us … We are very, very close to being able to ignore Trump most nights. I truly can’t wait … I hate him passionately.”

These were not the text messages of a liberal journalist feeling their spirit crushed by the Donald Trump era. They were, according to US court papers, the words of Tucker Carlson, one of the former US president’s biggest cheerleaders on the rightwing Fox News network.

A $1.6bn defamation lawsuit, brought by a voting machine maker that claims it was wrongly maligned, has pulled back the curtain on one of the most consequential relationships in modern political history: Trump and Fox News.

The private venting of Fox News’s primetime stars, expressing contempt for Trump and his election lies even as they told millions of viewers the opposite, has fueled perceptions that the long-running affair between America’s 45th president and most watched cable news network is on the rocks.

However, a glance at Fox News’s output over the last week suggests that, like love, it’s complicated. While Carlson and other primetime hosts may quietly be rooting for the Florida governor, Ron DeSantis, to beat Trump to the 2024 Republican primary nomination, they are already dropping hints about a readiness to jump back onboard the Trump train.

“It’s a toxic relationship,” said Michael Steele, former chairman of the Republican National Committee (RNC). “They are good and bad for each other at the same time. You’ve got to look at it through that prism to understand what’s going on here. Fox can’t do without Trump and Trump ultimately can’t do without Fox because he knows, at the end of the day, that’s the media vehicle through which he will be able to reach the widest audience of his supporters.”

The lawsuit has plunged Fox News, the dominant media force among conservatives, into one of the biggest crises in its 26-year history. Dominion Voting Systems argues that the network knowingly broadcast false claims that the election technology company was responsible for fraud in the 2020 presidential election.

Publicly released internal documents and depositions have revealed that, while Fox News hosts were promulgating Trump’s “big lie” of a stolen election, off air they were messaging their colleagues to say they did not believe a word of it.

In one text message exchange, Carlson, who hosts one of the most watched shows on cable news, said Trump has a talent to “destroy things. He could easily destroy us if we play it wrong.”

Later, addressing Trump’s four years as president, Carlson texted: “We’re all pretending we’ve got a lot to show for it, because admitting what a disaster it’s been is too tough to digest. But come on. There really isn’t an upside to Trump.”

Yet for years Carlson had been an enthusiastic champion of Trump. In a 2017 conversation with colleague Greg Gutfeld on the network, Carlson agreed that Trump was “the greatest president that ever will be”.

The paper trail goes all the way to the top. Rupert Murdoch, chair of Fox Corp, told the Fox News chief executive, Suzanne Scott, that hosts Sean Hannity and Laura Ingraham maybe “went too far” in pushing Trump’s election fraud claims on the network. Murdoch also called the voter fraud claims “really crazy stuff” in a text message.

The documents also paint a portrait of Fox News living in fear of bleeding its audience to even more extreme rivals such as Newsmax and the One America News Network. Bill Sammon, a Fox Washington news executive, is quoted as saying: “It’s remarkable how weak ratings make good journalists do bad things.”

On election night the network called – correctly – that Democrat Joe Biden had beaten Trump in the battleground state of Arizona, prompting a furious backlash from Trump’s supporters. One internal email said: “Holy cow, our audience is mad at the network.” Another noted: “They’re FURIOUS.”

Fox News dropped from first to third in the news network ratings between the 3 November 2020 election and Biden’s inauguration on 20 January 2021, according to Nielsen. Thousands of its viewers flocked to the more conservative Newsmax, where primetime viewership shot from 58,000 the week before the election to 568,000 the week after.

Carlson wrote to a producer: “Do the executives understand how much credibility and trust we’ve lost with our audience? We’re playing with fire, for real … an alternative like Newsmax could be devastating to us.”

Dominion argues that Fox executives decided to push false narratives to entice their audience back. It points to outlandish conspiracy theories promoted by Trump allies such as lawyer Sidney Powell on programs hosted by Maria Bartiromo and Lou Dobbs.

Matt Gertz, a senior fellow at the watchdog group Media Matters, said: “You can see the hosts worried that the network they had helped to build for years was basically going to collapse, that their viewers were turning on them, that executives were scrambling for a way to get the viewers back.”

There had effectively been a revolving door between the Trump White House and Fox News; his last press secretary, Kayleigh McEnany, is a regular on the network. But as the dust settled after the January 6 insurrection and Biden’s inauguration, the relationship cooled. Trump no longer called in to Fox & Friends to ramble at will. The network dropped his daughter-in-law, Lara Trump, as a contributor, ostensibly because of a ban on political activity.

It was a potentially serious blow to the man looking to win back the White House in 2024. Frank Luntz, a consultant and pollster, said: “Donald Trump needs Fox News more than Fox needs Donald Trump because Trump doesn’t have easy access to an uncritical media like he did in 2016. There is no alternative for him. He can’t go to CNN or MSNBC. He does have to go to Newsmax, and that just does not have the reach of these other cable news channels.”

Worse still for Trump, Fox News found a new Chosen One. It reportedly asked DeSantis to appear on air 113 times, or nearly once a day, during one four-month spell and was given exclusive access to his signing of a contentious election law. Reelected in a landslide last November, DeSantis is a culture warrior with a flair for “owning the libs”. The attraction was obvious.

Joe Walsh, a former Republican congressman, explained: “Fox News knows exactly what their audience wants. Their audience wants a guy like Trump. They want a bully. They want a son of a bitch. They want somebody who will go after woke. They want an authoritarian. So Fox is going to give them what they want.

“Fox has made the determination that they don’t think Trump can win in ‘24, which is why they’re pushing DeSantis. Once they realise that Trump is going to be the nominee, then everybody will fall in line like they did last time.”

When Trump supporters gathered at last week’s Conservative Political Action Conference (CPAC) in Oxon Hill, Maryland, both DeSantis and Fox News’s big names stayed away. Instead the Newsmax and other fringe rightwing media held sway. Trump ally Steve Bannon accused Fox News of disrespecting the former president, stating: “You’ve deemed Trump’s not going to be president. Well, we deem you’re not going to have a network.”

It was, perhaps, the equivalent of a cathartic marital row. A day later, something changed: Fox News carried the whole of Trump’s one hour, 45 minute address to CPAC, a departure from its distinctly tepid response to his 2024 campaign events. “I hope Fox doesn’t turn off, but we did much better in 2020 than we did in 2016,” he said pointedly.

Then, on Monday, Carlson presented selective excerpts of security footage from the US Capitol attack to spin the false narrative that January 6 was in fact a peaceful protest. He was widely condemned by both Democrats and Republicans – but Trump said on his social media platform, “congratulations to Tucker Carlson on one of the biggest ‘scoops’ as a reporter in US history”.

As the week wore on, Carlson praised Trump’s “bold plans” for 2024, telling viewers: “He is saying things that are really interesting, not rehashes at all.” Host Sean Hannity, “privately disgusted” with Trump according to court documents, played clips of an interview Trump had done on his radio show.

To observers, it was a sign that the on-off Trump-Fox affair could soon be on again, especially if, as opinion polls currently suggest, the former reality TV star surges ahead the Republican primary.

Walsh observed: “If you did a private poll of every conservative media talker and conservative network and every Republican elected official, 80 to 90% of them privately would want Trump gone and want DeSantis to be the guy. Tucker Carlson doesn’t want Trump to run again. Hannity, Trump’s cheerleader, doesn’t want Trump to run again.

“That’s how they all feel privately and they’re all hoping that somebody does their dirty work. Fox News is hoping that Trump will implode or get indicted or die or whatever but Fox News, we know, will follow their audience and, if Trump stays in and he’s the man, Fox News will be right there, his biggest cheerleader again.”

The bottom line is ratings or, to put it another way, dollars.

Tara Setmayer, a senior adviser to the Lincoln Project, an anti-Trump group, said: “Fox have already demonstrated that they will move and calibrate their news coverage based on what the audience demands and, as of right now, the demand still overwhelmingly is for Donald Trump.”

Setmayer, a former Republican communications director on Capitol Hill, added: “This an example of a dysfunctional co-dependent relationship. They need each other, whether they want to admit it or not.”