The cabinet is to meet formally this morning amid splits at the top of government over the future of the prime minister, with Home Secretary Shabana Mahmood among a number of ministers calling for Sir Keir Starmer to set out a timetable for his resignation.
It is understood Mahmood is in the minority in the cabinet over whether Sir Keir should set out a timetable.
Six ministerial aides - the lowest rung of government - have been replaced by No 10, after they either quit or called for Sir Keir to set out a timetable for his replacement.
And the tally of Labour MPs calling for Sir Keir to resign or set out a timetable for resignation has reached 72.
The list of ministerial aides who quit on Monday included Joe Morris, Parliamentary Private Secretary (PPS) to Health Secretary Wes Streeting, a potential leadership contender.
Morris said the prime minister "no longer has the trust or confidence of the public".
Melanie Ward, PPS to Deputy Prime Minister David Lammy, Naushabah Khan, PPS to Cabinet Office Minister Darren Jones, and Tom Rutland, PPS to Environment Secretary Emma Reynolds, also resigned.
Another two joined calls for Sir Keir to set out a timetable for his departure: Gordon McKee, PPS to Pensions Secretary Pat McFadden, and Sally Jameson, PPS to Home Secretary Shabana Mahmood.
In a speech earlier, the PM insisted he would prove the "doubters" wrong and would not be quitting.
He admitted the government had made mistakes but said it he had "got the big political choices right".
But pressure for him to go intensified through the day, building on calls for a timetable for his resignation from supporters of the Mayor of Greater Manchester, Andy Burnham.
Calls have also come from the right of the party, including those close to Streeting, for a swifter departure, which would exclude the chance of Burnham standing for the leadership.
Pressure has been mounting on Sir Keir after Labour lost almost 1,500 councillors in local elections across England, with a surge in support for Reform UK, and the Greens also eating into Labour's support in London and other urban areas.
The party was also kicked out of power in Wales, where it had enjoyed political dominance for a century, and returned just 17 of the 129 seats in the Scottish Parliament, its worst ever result at a Holyrood election.
In a statement, Morris said Labour councillors and candidates had "ended up taking the blame for decisions that were not theirs".
"Despite the prime minister's best efforts, voters simply do not accept that he can lead the change they voted for," the MP for Hexham said.
"It is in the best interests of the country and the party that the prime minister sets out a swift timetable to ensure that a new leader is in place to regain the confidence of the public and to ensure that the government can deliver on the commitments it has made."
Rutland, the MP for East Worthing and Shoreham, said: "It is clear to me that the prime minister has lost authority not just within the Parliamentary Labour Party but across the country and that he will not be able to regain it."
Khan, the MP for Gillingham and Rainham, said the PM had "lost the confidence of the public".
"I did not enter politics to stand by while we fail. We need a clear change of direction now and no game playing," she said.
"I am calling for new leadership, so that we can rebuild trust and deliver the better future that the British people voted for."
A PPS, which is an unpaid role, is appointed by a minister to act as their assistant.
Jameson, a PPS to Mahmood, said Sir Keir should "set out a clear timetable for his departure in September or shortly after".
The MP for Doncaster Central added that Labour's National Executive Committee (NEC) "should ensure that all potential candidates have the opportunity to stand and any timetable, I hope, would reflect this".
Earlier this year, the NEC blocked Burnham from standing as a candidate in the Gorton and Denton by-election.
Burnham has the support of many Labour MPs but any leadership contender must be a member of Parliament, so he would need time for another MP to trigger a by-election for him to stand.
Jonathan Hinder, Labour MP for Pendle and Clitheroe, also joined the call for Sir Keir to resign, telling BBC Newsnight that "no prime minister can survive this".
"The blunt reality is, and every single Labour MP will tell you this, he has never been an electoral asset," he said.
Hindler, who co-leads the Blue Labour caucus, added that Sir Keir's speech on Monday had been "tone deaf" and "at its worst, downright insulting".
He went on: "We're being swept away in our heartlands... and to come out in response to that and start talking about Brexit and having free movement again... those people are more bothered about what's going on here."
In an attempt to reset his premiership after Friday's election results, Sir Keir gave a speech promising to "face up to the big challenges".
He reiterated his desire for closer relations with the EU and announced British Steel would be nationalised, with legislation to be brought forward this week.
The PM also vowed not to walk away, saying this would "plunge our country into chaos, as the Tories did time and again".
There was temporary relief for Downing Street when Labour MP Catherine West pulled back from launching a leadership challenge.
Over the weekend, the north London MP had threatened to kick-start a contest by putting her name forward but, after listening to the PM's speech, she instead called on him to set out a timetable for his departure by September.
While not trying to become Labour leader herself, West had hoped to tempt others to launch a bid.
However, as the afternoon went on, growing numbers of Labour MPs called for the prime minister to go, delivering further blows to his authority.
Another potential leadership contender, former Deputy Prime Minister Angela Rayner, told a conference of the Communication Workers Union that "we as a party have to do better than this".
She said Sir Keir had "acknowledged the frustration" voters expressed through last week's election results but "we will be judged on actions and not just our words".
Rayner also reiterated her call for Burnham, who stood down as an MP in 2017, to be allowed to return to Parliament.
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