Tory leadership frontrunner Boris Johnson has refused to say whether he would keep the UK's ambassador to Washington in post following the leak of sensitive diplomatic messages.
The former foreign secretary sidestepped questions over whether he would allow Sir Kim Darroch to remain in the job until he is due to retire later this year, insisting it was "vital" the civil service is not politicised.
He made the comments during a televised head-to-head debate with his rival Jeremy Hunt, amid a day of high drama which saw Donald Trump describe Sir Kim as a "pompous fool" and a "very stupid guy" who had been foisted on the US.
Mr Johnson said: "I think it is absolutely vital that the advice that civil servants give to ministers should not be leaked by ministers and should not be commented on by ministers if civil servants are going to feel free to give that advice with the impartiality that they want."
But he refused to say whether he would keep Sir Kim in post, and instead he told the ITV debate: "It is vital that our civil service is not politicised by ministers leaking what they say. Whoever leaked that deserves to be eviscerated."
However his rival Mr Hunt, the Foreign Secretary, said he would "certainly" keep Sir Kim in the role.
"Who chooses our ambassadors is a matter for the United Kingdom Government and the United Kingdom prime minister, and I have made it clear if I am our next prime minister the ambassador in Washington stays because it is our decision," he said.
Earlier, Mr Hunt accused the US president of disrespecting the UK and Theresa May after Mr Trump's Twitter tirade about her "foolish" leadership.
In an extraordinary onslaught against an ally, Mr Trump used a Twitter post to attack the Prime Minister over Brexit, accusing her of ignoring his advice and "going her own foolish way".
Mr Hunt shot back, using Mr Trump's favoured social media platform to accuse the president of being "disrespectful and wrong" – which some likened to a "Love Actually moment", in reference to Hugh Grant's character in the romcom snapping at the American president.
In his explosive Twitter comments, Mr Trump said: "The wacky ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy.
"He should speak to his country, and Prime Minister May, about their failed Brexit negotiation, and not be upset with my criticism of how badly it was handled.
"I told Theresa May how to do that deal, but she went her own foolish way – was unable to get it done. A disaster!
"I don't know the ambassador but have been told he is a pompous fool."
Mrs May has made clear her full support for Sir Kim following the leak of diplomatic dispatches in which he described the White House as "inept" and "dysfunctional".
Downing Street said Sir Kim remained in post after Mr Trump warned on Monday the White House would have nothing more to do with him.
The first indication of that became evident when the ambassador was "uninvited" to a White House dinner on Monday evening, held in honour of the Emir of Qatar.
Sir Kim was also not attending a meeting between Ivanka Trump and the International Trade Secretary Liam Fox in Washington.
Following the meeting, a Department for International Trade spokesman said: "Secretary of state Dr Liam Fox met with Ivanka Trump in Washington DC this afternoon, accompanied by Britain's Trade Commissioner Antony Phillipson.
"They continued discussions from their recent meeting in London on women's empowerment, particularly in relation to international trade and also the forthcoming G7."
The issue was discussed at Cabinet, where Mrs May denounced the leak of Sir Kim's dispatches as "unacceptable" and stressed it was important ambassadors were able to provide "honest, unvarnished" advice to ministers.
Mr Trump's outspoken attack, the most strident public criticism of a British prime minister by a US president in decades, caused dismay in Whitehall.
It comes just a month after the Government rolled out the red carpet for the president for a state visit in which he praised the enduring strength of the "special relationship".
A formal civil service leak inquiry has been launched, but MPs called for the police to investigate.
The Foreign Affairs Committee, which will hear from senior Foreign Office mandarin Sir Simon McDonald on Wednesday, has written to the Prime Minister, Foreign Secretary and Metropolitan Police Commissioner Cressida Dick about the leak.
In his letter to Scotland Yard calling for a police investigation, committee chairman Tom Tugendhat said: "This appears to be a serious criminal act."