Bannon, who returned to rightwing site Breitbart News after being forced out of the White House in August, recalled an Oval Office meeting in which he accused Ivanka of being “the queen of leaks”. The first daughter allegedly retorted: “You’re a f****** liar!”

He also condemned Ivanka over her handling of the recent US Senate special election in Alabama, where Republican candidate Roy Moore denied accusations of sexual misconduct with teenagers. Ivanka said pointedly during the campaign: “There is a special place in hell for people who prey on children.”

Bannon, who supported Moore despite the allegations only to see him lose the Republican heartland to a Democrat, responded in the Vanity Fair interview: “What about the allegations about her dad and that 13-year-old?” – a reference to an unproven allegation from a California woman that Trump raped her as a teenager (last year the woman dropped a lawsuit making the claim). Trump has faced multiple claims of sexual misconduct and denies all of them.

Bannon added to Vanity Fair: “Ivanka was a fount of bad advice during the campaign.”

As for Kushner, Bannon made little attempt to disguise his contempt. “He doesn’t know anything about the hobbits or the deplorables” – using two ironic terms for Trump supporters.

It was Kushner who reportedly encouraged the president to fire FBI director James Comey, a move that could come back to haunt him during the investigation into alleged collusion with Russia in the election campaign. Bannon said: “It’s the dumbest political decision in modern political history, bar none. A self-inflicted wound of massive proportions.”

There was never much love lost between Bannon and “Javanka” as, like medieval courtiers, they competed for the ear of the president. Bannon, 64, has an unkempt appearance – one congressman recently remarked that he looks like a “dishevelled drunk” – and grew up in a working-class, Irish Catholic family in Virginia. He embodies Trump’s instincts of insurgent nationalism and anti-globalisation and has been accused of stoking anti-Semitism, which he denies.

Kushner is Jewish and, at 36, from a different generation, with a clean-cut smartness that contrasts with Bannon’s scruffiness. The scion of a New York property empire, he was previously a Democratic donor who mingled with the wealthy east coast elites that Bannon despises. Ivanka, also 36, also belongs to the “New York faction” and is seen as the favourite of Trump’s five children.

Liberal observers had expressed a hope that “Javanka” would tame Trump’s wilder impulses but there have been constant disappointments. The president’s decision to pull the US out of the Paris climate deal was a notable victory for Bannon.

Rick Tyler, a Republican analyst and co-founder of consulting firm Foundry Strategies, said: “These things are very difficult when family is involved with any elected official. They have a different relationship with the principal and it’s very difficult to work around if there’s a problem.

“I don’t know what Jared and Ivanka bring to the administration. Some said they were going to moderate the president and keep him presidential but there’s not much evidence of that. I think a lot of advice they provided to the president has not been good.”

Ivanka came under fire this week after promoting Republicans’ sweeping tax reform, her father’s first major legislative achievement. During a sycophantic interview by Fox News, which praised her for securing an increase in the child tax credit, she claimed: “I’m really looking forward to doing a lot of travelling in April when people realise the effect that this has … The vast majority will be [doing their taxes] on a single postcard.” Critics were quick to point out the postcard was a publicity stunt and a promise that has not been kept.

A headline in The Washington Post read: “Once again, Ivanka Trump shows off her cluelessness.” Columnist Jennifer Rubin wrote: “She’s a walking advertisement for the danger of nepotism, an exemplar of class privilege and a perfect representative for Republican know-nothingism. She was supposed to be the brains of the family and the moral ballast; instead, she’s a self-righteous enabler.”

Kushner, meanwhile, appears to be in retreat. Once ubiquitous, his public appearances have declined. It has been widely reported that his gigantic portfolio has shrunk and his influence is on the wane, raising questions over how long “Javanka” will remain in Washington.

This may in part be because of speculation that he will be the next big fish caught in special counsel Robert Mueller’s investigation into Russian meddling in last year’s presidential election. There has been a steady drip of revelations about his part in the intrigue. Kushner was also forced to apologise in July for filing incomplete security clearance forms. He has denied any kind of collusion with Russia.

Also, according to media reports, Kushner was key to Trump’s decision to recognise Jerusalem as the capital of Israel, a move that earned considerable international blowback. This week the UN general assembly voted by a huge majority to reject America’s stance.

Tyler, former campaign spokesman for Republican Ted Cruz, added: “Jared has shrunken from the spotlight. He seemed to be seen in every photo and was keenly aware of where the photographers were and what type of lens they were using. But we never heard from him and, when we did, it wasn’t terribly impressive.

“Usually when we put people in positions of great responsibility and authority we have knowledge of their commensurate qualifications and experience; with Jared we know of none.”