The storming of the US Capitol has triggered Rupert Murdoch's media empire to call time on Donald Trump, with The Wall Street Journal saying the president should resign and even acolytes on Fox News telling viewers he has reached the end of his shelf life.

Murdoch's right-wing outlets helped propel the property tycoon-turned reality TV star to the White House in 2016, remaining steadfastly loyal for four years before cracks in the alliance began to appear on re-election day.

Wednesday's rampage around the halls of Congress by a pro-Trump mob, leading to five deaths and worldwide uproar and condemnation, appears to have sounded the death knell for the relationship, although the outlets face a tricky balancing act keeping his supporters.

"Trump's no longer going to be President of the United States and the odds of him getting back to that position someday keep decreasing. So as his power decreases there's a logic that says, 'Let him go, cut him loose,'" New York University journalism professor Mitchell Stephens told AFP.

On Thursday, The Wall Street Journal's editorial board did just that, calling on the 74-year-old Trump to step down before being impeached.

"This week has probably finished him as a serious political figure," said the column, adding: "It is best for everyone, himself included, if he goes away quietly."

The New York Post tabloid, another staple of the 89-year-old Murdoch's vast media portfolio, also lashed out at Trump with columnist Michael Goodwin writing that the outgoing president was responsible for "this day of infamy."

"This time, there is no defense of him. He owns this," wrote Goodwin.

Even Tucker Carlson, the second most-watched TV presenter in the US, who has remained fiercely loyal to Trump for the past five years, accused him of "recklessly encouraging" the rioters with an inflammatory speech in Washington earlier in the day.

"At some point you've got to wonder where our country is putting all of its energy. Is any single president, anyone, worth all of this time and attention?" Carlson said during one of his monologues on Fox News.

With politicians from across the spectrum and world leaders rushing to condemn the actions of the rioters, Mark Feldstein, a journalism professor at the University of Maryland, says the outlets are "trying to protect their own reputations."

Money, money, money

"I think they're afraid that Trump has finally gone too far. They're putting some distance between themselves and Trump for their own self-preservation.

"(But) let's not forget they are the ones who enabled Trump... so they created a Frankenstein monster and they have no one but themselves to blame," he told AFP.

Fox News faces a conundrum -- how to put enough distance between itself and Trump without alienating his loyal fan base who tune in nightly expecting to hear good things about their man.

"It's kind of an interesting dance there," Matt Jordan, associate professor of media studies at Penn State University, told AFP.

"Probably what Murdoch's doing is trying to have it both ways," he added.

For Feldstein, the decisions will be made based on business, not points of principle.

"It's not about ideology, it's about money, it's about ratings, profits," he said.

Fox News's maneuvering is made all the more delicate by a host of smaller right-wing upstart channels, most notably Newsmax and One America News Network, that are grabbing market share by being even further to the right.

Trump's base had already accused Fox News of abandoning their cause after the network infuriated Trump on election night by calling Arizona for Democrat Joe Biden, who will be inaugurated as president on January 20.

Even without Trump, Northwestern University professor Jon Marshall expects Murdoch outlets to "focus sharply on attacks against the Democrats that are going to be in power and build outrage against them."

"They may be able to hold to their audience by that method," he said.

But the temptation of Trump may never be far away.

"Biden is going to be pretty boring," said Feldstein.

"Television is good at covering emotion, conflict, personalities. That's why Trump was such nectar for them."