A billionaire Tory donor has warned Boris Johnson's premiership is "past the point of no return" and said the embattled Prime Minister should step down.
Hedge fund boss John Armitage, who has donated more than £3m to the Conservatives in the past, said leaders "should leave" if they lose their "moral authority" - and branded the lack of honour in modern politics "incredibly distressing".
Asked if the Prime Minister was "past the point of no return", he told the BBC: "Well, personally yes."
Mr Armitage has stopped donating cash to the Tories as things stand but remains a party member.
The intervention will come as a blow to Mr Johnson as he tries to stabilise his crisis-hit premiership with a mini-reshuffle to bring more loyalists into his top team.
Ahead of today's PMQs' clash, Mr Johnson is also under intense pressure to apologise for making a Jimmy Savile slur against Keir Starmer last week.
The row blew up again when Mr Starmer was beset by protesters on Monday night, with some repeating the discredited claim that he failed to prosecute the notorious paedophile when he was Director of Public Prosecutions.
The PM is seeking to build bridges with Tory MPs fed up by months of rows over partygate and sleaze.
But Mr Armitage said the current political situation was "tremendously upsetting".
He said: "I feel that if you lose moral authority, and if you do things, which, you know, the average person, your mother, someone you try to explain, someone who you admire, if you do something or say something which on the front page of the Sunday Times looks terrible, and you do that consistently, and you betray a sense of not really caring, I think you should leave.
"And I find the lack of honour inherent in modern politics incredibly distressing."
He expressed doubt about changes in No 10, saying: "God above. What about a sense of personal responsibility?
"'Oh I'm going to change my chief of staff and it will all be fine.' Oh really?"
Mr Armitage has also donated cash to Labour, including £12,500 in March 2021. He handed £50,000 to the Tories in December 2020.
A Conservative spokesperson said the government remained "fully focused on delivering for the British people".
Meanwhile, Health Minister Ed Argar suggested the Prime Minister not apologise for his Jimmy Savile remarks.
"The Prime Minister... has been very clear - he's clarified what he was talking about," he told Sky News.
"He's clarified that he was talking about Sir Keir in the context of his leadership role at the CPS. Just as, quite rightly, Sir Keir holds him to account for his leadership role over the Government.
"That don't mean personal responsibility for individual decisions, but that's the context, and the Prime Minister has clarified that.
"And I'll be honest with you, I suspect that's what you will hear from the Prime Minister later."
