Spare a thought for Donald Trump’s media cheerleaders. As a sea of scandal laps at the door of the Oval Office, they are faced with a seemingly impossible challenge: how to report the news all of America is talking about without damaging the man they helped persuade 63 million of its citizens to vote for last November.

Two weeks ago, Fox News, Rupert Murdoch’s right-wing cable news channel, thought it had found the perfect answer — change the subject. In place of stories about the Trump campaigns links to Russia, the firing of FBI Director James Comey and the appointment of a special prosecutor, it decided to peddle a bizarre and bogus conspiracy theory about the year-old murder of Seth Rich, a young Jewish staffer for the Democratic party.

The gambit, which led Mr Rich’s parents to beg the channel to stop exploiting their son’s tragic death, now appears to have boomeranged. Rather than distracting viewers’ attention from the president’s growing legal and political problems, it threatens the future of Fox’s highest-rated show and one of Mr Trump’s most vocal supporters in the media, Sean Hannity.

In the early hours of 10 July last year, 27-year-old Mr Rich was gunned down near his home in Washington DC in an apparent botched robbery. An employee of the Democratic National Committee (DNC), he had recently been hired by Hillary Clinton’s presidential campaign and was excitedly planning a four-month move to her New York headquarters.

Shortly after his death, Julian Assange began to hint that Mr Rich had been the source of the massive leak of the DNC’s emails to Wikileaks. The emails were subsequently published by it, helping to inflict huge damage on Mrs Clinton as she attempted to unite the Democratic party following a bruising primary fight against Senator Bernie Sanders.

Ten months later, and in the immediate aftermath of Mr Comey’s dismissal by Mr Trump, the story resurfaced when a private investigator claimed to have uncovered “tangible evidence” that Mr Rich had been in communication with Wikileaks. While those claims were swiftly debunked, Fox chose to air the allegations prominently on its website, while Mr Hannity began to relentlessly promote them on his primetime show.

For Mr Hannity, the story served three overlapping purposes. It not only shifted attention away from the fallout of Mr Comey’s firing, it also not-too-subtly implied that Mrs Clinton and her campaign may some how have been involved in Mr Rich’s death. Perhaps most importantly, as Mr Hannity himself tweeted, “If Seth was wiki source, no Trump/Russia collusion”. Indeed, Mr Assange’s original attempt to implicate Mr Rich in the leak appears similarly intended to distract the focus from the true source of his windfall: Kremlin-allied hackers.

As the baseless story — Mr Rich’s work on voter turnout for the party never gave him access to the trove of leaked emails — garnered attention, his grieving parents appealed to Fox. “Seth’s death has been turned into a political football,” they wrote. “The amount of pain and anguish this has caused us is unbearable.”

Such tactics have been attacked by decent-minded conservatives, among them many on the Jewish right who have long opposed Mr Trump. “Fox’s jaw-dropping unprofessionalism and dishonesty were matched only by its cruelty,” wrote the columnist Jennifer Rubin, while foreign policy expert Max Boot accused the channel of being “morally bankrupt”.

A campaign to persuade companies to pull adverts from Mr Hannity’s show is gathering pace. Crowne Plaza, cars.com and the insurance company USAA are among the household names who have stopped their advertising. Mr Hannity’s ratings, already on the slide, have tumbled further.

Hit where it hurts, Fox has begun to back-pedal. It removed its original website story, saying it had failed to meet a “high degree of editorial scrutiny”. Without apologising or retracting, Mr Hannity last week said that “out of respect” for Mr Rich’s family, he would stop talking about the story. Within 24 hours, however, he tweeted: “I am closer to the TRUTH than ever. Not only am I not stopping, I am working harder. Stay tuned!” For now, loyalty to his most avid fan in the White House appears to have trumped both decency and commercial good sense.