Donald Trump has dismissed staff from the Oval Office as readily as he fired contestants from the boardroom of Trump Tower as host of NBC’s The Apprentice.

Few have lingered longer in the memory than Anthony Scaramucci.

Since being sacked as White House director of communications after just 11 days in July 2017, the former investment banker has dined out on his experience of the inner workings of the Trump administration, appearing regularly as a talking head on innumerable TV shows and podcasts to offer insight into the president and speculate on his motivations.

Recently though, “The Mooch” has rounded on a man he previously defended, even after that humiliating dismissal, and has found himself drawn into an intense, cross-media feud with the president that shows no sign of ending.

Matters came to a head on Monday when Mr Trump responded to his former employee telling CNN’s New Day he planned to assemble a coalition of former Trump cabinet officials to denounce the president ahead of the 2020 election by lashing out at him in an angry two-part tweet, describing his fellow New Yorker as a “highly unstable ‘nut job’ who was with other candidates in the primary who got shellacked, & then unfortunately wheedled his way into my campaign”.

Trump protests: President visits Texas and Ohio after mass shootings Show all 31 1 /31 Trump protests: President visits Texas and Ohio after mass shootings Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators chant as they protest the arrival of President Donald Trump outside Miami Valley Hospital after a mass shooting that occurred in the Oregon District AP Trump protests: President visits Texas and Ohio after mass shootings El Paso Trump headed to El Paso, after visiting Dayton, Ohio to offer a message of healing and unity, but he was met by hostility in both places by people who fault his own incendiary words as a contributing cause to the mass shootings AP Trump protests: President visits Texas and Ohio after mass shootings El Paso, University Medical Centre US President Donald Trump greets first responders as he visits El Paso Regional Communications Centre AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso, University Medical Centre An anti-Trump protestor holds a sign as police are lined up outside University Medical Centre Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso Demonstrators hold a sign as the motorcade carrying President Donald Trump departs a joint operations center after meeting with first responders after the El Paso mass shooting, Wednesday, Aug. 7, 2019, in El Paso, Texas. (AP Photo/Evan Vucci) Evan Vucci AP Trump protests: President visits Texas and Ohio after mass shootings El Paso Anti-Trump protesters hold a banner outside the makeshift memorial to the victims of the WalMart shooting that left a total of 22 people dead, in El Paso, Texas, on August 7, 2019. - President Donald Trump consoled victims of a mass shooting in Ohio on Wednesday but protesters and opponents denounced what they say is his extremist rhetoric on race and immigration. The president's trip to Dayton, where nine people were gunned down over the weekend, was to be followed immediately after by a stop in the border city of El Paso, Texas, where 22 were murdered. (Photo by Mark RALSTON / AFP)MARK RALSTON/AFP/Getty Images MARK RALSTON AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators gather to protest the arrival of President Donald Trump outside Miami Valley Hospital after a mass shooting that occurred in the Oregon District early Sunday morning, Wednesday, Aug. 7, 2019, in Dayton. Twenty-four-year-old Connor Betts opened fire in Dayton early Sunday, killing several people including his sister, before officers fatally shot him. (AP Photo/John Minchillo) John Minchillo AP Trump protests: President visits Texas and Ohio after mass shootings El Paso Democratic presidential candidate Beto ORourke hugs a woman at a makeshift memorial outside Walmart honoring victims of the mass shooting there which left 22 people dead. Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso Anti-Trump protesters hold signs outside the makeshift memorial to the victims of the WalMart shooting that left a total of 22 people dead, in El Paso, Texas, on August 7, 2019. - President Donald Trump consoled victims of a mass shooting in Ohio on Wednesday but protesters and opponents denounced what they say is his extremist rhetoric on race and immigration. The president's trip to Dayton, where nine people were gunned down over the weekend, was to be followed immediately after by a stop in the border city of El Paso, Texas, where 22 were murdered. (Photo by Mark RALSTON / AFP)MARK RALSTON/AFP/Getty Images MARK RALSTON AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso Marisela Hernandez holds sign to protest the visit of President Donald Trump to the border city after the Aug. 3 mass shooting in El Paso, Texas, Wednesday, Aug. 7, 2019. Aiming to play the traditional role of healer during national tragedy, President Donald Trump paid visits Wednesday to cities reeling from the mass shootings. (AP Photo/Andres Leighton) Andres Leighton AP Trump protests: President visits Texas and Ohio after mass shootings El Paso, University Medical Centre An anti-Trump demonstrator holds up a placard outside the University Medical Center, where U.S. President Donald Trump holds a meeting with first responders in the wake of last weekend's mass shootings at a Walmart store, in El Paso, Texas, U.S., August 7, 2019. REUTERS/Jose Luis Gonzalez JOSE LUIS GONZALEZ Reuters Trump protests: President visits Texas and Ohio after mass shootings El Paso, University Medical Centre President Trump and First Lady Melania Trump greet PFC Glendon Oakley (second right), who saved several lives during the mass shooting in Texas AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators chant as they protest the arrival of President Donald Trump outside Miami Valley Hospital after a mass shooting that occurred in the Oregon District early Sunday morning, Wednesday, Aug. 7, 2019, in Dayton. (AP Photo/John Minchillo) John Minchillo AP Trump protests: President visits Texas and Ohio after mass shootings El Paso, University Medical Centre An anti-Trump demonstrator holds up a placard as police block the area outside the University Medical Center, where U.S. President Donald Trump holds a meeting with first responders in the wake of last weekend's mass shootings at a Walmart store, in El Paso, Texas, U.S., August 7, 2019. REUTERS/Jose Luis Gonzalez JOSE LUIS GONZALEZ Reuters/Amanda Voisard Trump protests: President visits Texas and Ohio after mass shootings El Paso Beto ORourke consoles a man at the makeshift memorial outside Walmart Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso, University Medical Centre An anti-Trump demonstrator yells near police outside the University Medical Centre Reuters Trump protests: President visits Texas and Ohio after mass shootings El Paso TOPSHOT - El Paso residents protest against the visit of US President Donald Trump to the city after the Walmart shooting that left a total of 22 people dead, in El Paso, Texas, on August 7, 2019. - President Donald Trump consoled victims of a mass shooting in Ohio on Wednesday but protesters and opponents denounced what they say is his extremist rhetoric on race and immigration. The president's trip to Dayton, where nine people were gunned down over the weekend, was to be followed immediately after by a stop in the border city of El Paso, Texas, where 22 were murdered. (Photo by Mark RALSTON / AFP)MARK RALSTON/AFP/Getty Images MARK RALSTON AFP/Getty Images Trump protests: President visits Texas and Ohio after mass shootings Dayton President Donald Trump and First Lady Melania Trump arrive at Wright-Patterson Air Force Base AP Trump protests: President visits Texas and Ohio after mass shootings El Paso Makeshift memorial for victims of the shooting that left a total of 22 people dead at the Cielo Vista Mall Walmart AFP/Getty Images Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators gather to protest the arrival of President Donald Trump outside Miami Valley Hospital after a mass shooting that occurred in the Oregon District early Sunday morning, Wednesday, Aug. 7, 2019, in Dayton. (AP Photo/John Minchillo) John Minchillo AP Trump protests: President visits Texas and Ohio after mass shootings President Trump greets Dayton Mayor Nan Whaley as he arrives at Wright-Patterson Air Force Base AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators gather to protest the arrival of President Donald Trump outside Miami Valley Hospital after a mass shooting that occurred in the Oregon District early Sunday morning, Wednesday, Aug. 7, 2019, in Dayton, Ohio. Twenty-four-year-old Connor Betts opened fire in Dayton early Sunday, killing several people including his sister, before officers fatally shot him. (AP Photo/John Minchillo) John Minchillo AP Trump protests: President visits Texas and Ohio after mass shootings Dayton Damon Smith presents a message to President Donald Trump beside a makeshift memorial in Dayton AP Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators gather in front of an inflatable "Baby Trump" to protest the presidents arrival AP Trump protests: President visits Texas and Ohio after mass shootings Miami Valley Hospital, Dayton Demonstrators gather to protest the arrival of President Donald Trump outside Miami Valley Hospital after a mass shooting that occurred in the Oregon District early Sunday morning, Wednesday, Aug. 7, 2019, in Dayton. President Donald Trump is headed to Dayton and El Paso, Texas on Wednesday to offer a message of healing and unity, but he will be met by unusual hostility in both places by people who fault his own incendiary words as a contributing cause to the mass shootings . (AP Photo/John Minchillo) John Minchillo AP Trump protests: President visits Texas and Ohio after mass shootings El Paso A photo of victim Javier Amir Rodriguez, a 15-year-old sophomore Getty Trump protests: President visits Texas and Ohio after mass shootings Dayton Demonstrators protest the visit of US President Donald Trump to the site of the mass shooting in Dayton, Ohio, on August 7, 2019. - Nine people were killed on August 4 in the city's popular Oregon District. (Photo by Megan JELINGER / AFP)MEGAN JELINGER/AFP/Getty Images MEGAN JELINGER AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso A message is left for Donald Trump AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso Signs and flags adorn the makeshift memorial for victims of the shooting that left a total of 22 people dead at the Cielo Vista Mall Walmart, in El Paso, Texas, on August 7, 2019. (Photo by Mark RALSTON / AFP)MARK RALSTON/AFP/Getty Images MARK RALSTON AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso People hug at the makeshift memorial AFP/Getty Trump protests: President visits Texas and Ohio after mass shootings El Paso People pray at the makeshift memorial AFP/Getty

Mr Scaramucci, the president claimed, had “made a fool of himself, bad on TV. Abused staff, got fired” and had been a “mental wreck” during his short tenure at 1600 Pennsylvania Avenue as a result of marital troubles.

The exact words that had likely sparked the president’s ire? Mr Scaramucci calling him “unstable”.

“I’m in the process of putting together a team of people that feel the exact same way that I do,” Mr Scaramucci had told CNN’s Alisyn Camerota. “This is not a ‘Never Trump’ situation. This is not just screeching rhetoric. This is – OK, the guy is unstable. Everyone inside knows it, everyone outside knows it. Let’s see if we can find a viable alternative.”

He added: “Moreover, I have to get some former cabinet officials in unity to speak up about it. They know it’s a crisis.” Mr Scaramucci did not provide any names but predicted that within a few months there will be a “trove” of people willing to speak out against Mr Trump.

Weeks of the former aide’s persistent niggling criticism had finally gotten to the commander-in-chief but just what was it that caused the worm to turn in the first place?

Previously respectful towards his old meal ticket in interviews, Mr Scaramucci’s first real act of dissent came when he spoke out against the resignation of Sir Kim Darroch as British ambassador to the US following the leaking of unflattering remarks made by the diplomat against the “uniquely dysfunctional” administration in early July.

But his measured defence of Sir Kim as a “champion of freedom” who deserved better than a forced resignation under pressure from the White House was nothing compared to the much more forthright attack on President Trump that followed a week later over his racist tweets.

The president had told Democratic congresswomen Alexandria Ocasio-Cortez, Ilhan Omar, Rashida Tlaib and Ayanna Pressley to “go back and help fix the totally broken and crime infested places from which they came”, prompting an indignant response from Democrats on Capitol Hill, members of the press and the handful of Republicans that reporters had managed to corner in the corridors of Congress.

“Would @realDonaldTrump ever tell a white immigrant – whether 1st, 2nd, 3rd or 4th+ generation – to “go back to your country”? No. That’s why the comments were racist and unacceptable,” Mr Scaramucci tweeted. “America is a nation of immigrants founded on the ideals of free thought and free speech.”

The Mooch appeared on Howard Kurtz’s Fox News show Media Buzz five days later to warn that “if [President Trump] keeps going down this path, a Republican will primary him … You cannot divide the country as the president of the United States … These are racist comments, period full stop. The fact that we even have to debate this means that the president is in trouble on this.”

As Mr Trump lurched onwards from that scandal to the next, his former disciple emerged as a leading, if highly unlikely, critic of the administration, with all the zeal of a fresh convert.

The president managed to resist his provocations until 8 August when he finally snapped after catching Mr Scaramucci’s appearance with Chris Matthews on MSNBC’s Hardball, in which he characterised Mr Trump’s visit to a hospital in El Paso, Texas, to console those injured in the recent mass shooting as “a catastrophe”.

“The facts are he did not do well on the trip, because if the trip is being made about him and not the demonstration of compassion and love and caring and empathy for those people, then it becomes a catastrophe for him, the administration, and it’s also a bad reflection on the country,” Mr Scaramucci said.

Angered, President Trump accused his ex-spokesperson of bearing a grudge after being denied the chance to play a meaningful role in the administration (an accusation he also levelled at ex-FBI special counsel Robert Mueller during the Russia investigation) and of profiteering through his regular TV appearances as an insider pundit.

“[Scaramucci] now seems to do nothing but television as the all time expert on ‘President Trump’. Like many other so-called television experts, he knows very little about me,” the commander-in-chief tweeted.

This in turn led Mr Scaramucci to tell Bloomberg News: “At this time I cannot support his re-election and we need to think about someone new to be at the top of the ticket.”

“By the way, bullying is very anti-American. Should we send him back?” he added, pointedly referring to what had become a pet issue of the first lady, Melania Trump. “The dam is going to break. People are embarrassed now.”

Taking to his new role as the unexpected face of the resistance, the combative, if undeniably opportunistic Anthony Scaramucci has continued to take the fight to the president.

“Trump isn’t racist. He’s worse,” he tweeted on 16 August. “He’s so narcissistic he doesn’t see people as people. It’s why he doesn’t have any real friends. It’s why he gives a thumbs up next to an orphaned baby after a mass shooting. Everybody is an obstacle or a stepping stone.”

But perhaps his most telling post came on 12 August, when he wrote: “To those asking, ‘what took so long?’ You’re right. I tried to see best in @realDonaldTrump​ based on private interactions and select policy alignment. But his increasingly divisive rhetoric – and damage it’s doing to fabric of our society – outweighs any short-term economic gain.”

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He elaborated on the reason for his change of heart in an op-ed for The Washington Post on 20 August, lamenting his former support for the president, attacking his reaction the neo-Nazi rally in Charlottesville and child separation policy at the US-Mexico border and stating: “This isn’t a Road to Damascus moment; my concerns have been building publicly for a while. And I’m not seeking absolution. I just want to be part of the solution.”

Who might appear in his coalition of ex-cabinet members is anyone’s guess – Rex Tillerson? John Kelly? Kirstjen Nielsen? – as the list of excommunicated Trump administration officials is long indeed.