Sue Gray's report into lockdown-breaking parties in Downing Street is so damaging that it could leave Boris Johnson with no choice but to resign, senior officials are said to believe.
The top civil servant was forced to put off publishing her findings until Scotland Yard finishes its own investigation into rule-flouting gatherings in No10 and Whitehall.
Ms Gray's initial report into 16 lockdown parties, which was published in January, tore into "failures of leadership and judgement" in No10.
The full report is understood to be highly critical of the Prime Minister, both for attending some of the events and the culture in No 10 under his leadership.
A senior official familiar with the contents of the report told the Times that the findings are “damning” for Mr Johnson and could spell the end of his time as prime minister.
“Sue’s report is excoriating. It will make things incredibly difficult for the prime minister,” the official told the paper.
"There’s an immense amount of pressure on her — her report could be enough to end him.
“No official has ever been in a position like this before.”
The Prime Minister's official spokesman said no one in Downing Street had received a copy of the Sue Gray report yet.
Asked about the claims, he said: "I don't recognise those quotes."
It is widely believed in Westminster that the Prime Minister will try to cling onto power unless he is ousted by his own MPs.
Jittery Tories are bracing for a battering at the polls in the local elections in May, with some MPs admitting they are waiting until the result before deciding whether to submit a no-confidence letter.
But some are said to be privately making plans for Mr Johnson’s departure regardless of the election result.
One former Johnson backer told the Mirror: “I think we’ve gone past the tipping point. He’s lost public trust and once that’s gone, it’s hard to win back”.
Meanwhile, the i reported that some rebels are coordinating a push between 2019 intake Tories and moderate One Nation caucus to oust him.
The Prime Minister is understood to have attended at least six of the 12 events being investigated by the Metropolitan Police - and has already received a fine.
Scotland Yard issued Mr Johnson, his wife Carrie and Chancellor Rishi Sunak with £50 fines over a surprise birthday gathering for the PM in the Cabinet room in June 2020.
An ally had previously tried to defend him, saying he had been “ambushed by cake”.
Police have already issued fines for two boozy Whitehall leaving dos, and junior officials started to receive emails on Friday over the infamous “bring your own booze” party in the Downing Street garden in May 2020.
Mr Johnson has already admitted to briefly attending the event but tried to claim it was a work event.
More than 50 Downing Street staff were understood to have been in attendance at the do, which was organised by his principle principal secretary Martin Reynolds.
A witness said: “There were 40 people in the garden, including Boris and Carrie. There were long tables laden with drink, crisps, sausage rolls and other picnic food.
“It was a proper booze-up.”
Boris Johnson has not received any further fixed penalty notices for breaches of lockdown regulations in No 10, Downing Street said on Monday.
Mr Johnson has refused to resign despite issuing an apology and paying his fine earlier this month.
He is now subject to three Partygate investigations, which include the police probe, Ms Gray's report and a Commons Privileges Committee inquiry into whether he misled Parliament over the scandal.
On Sunday, Tory Party chairman Oliver Dowden claimed there was a “strong case” for him staying in No 10 and said Mr Johnson had “plenty more fuel in the tank”.
The prime minister is due to make a series of visits this week as part of the Conservative Party’s local election campaign.
Some Tory MPs believe Johnson will face a confidence vote shortly after the elections on May 5, if further fines issued by the police were followed by bad results for the PM.
Meanwhile, Labour leader Keir Starmer said he would keep pressing for Johnson to resign over the parties.
Mr Starmer said: "Boris Johnson and Rishi Sunak have broken the law and repeatedly lied to the British public.
"They must both resign. The Conservatives are totally unfit to govern. Britain deserves better."
Brexit opportunities minister Jacob Rees-Mogg described the Prime Minister as a “great man”.
“I don’t think people are losing faith in him,” he insisted.
“The socialists don’t like him, of course they don’t, that’s their job."
