Sir Keir Starmer has vowed he will not "walk away" after receiving cabinet backing despite calls from Scottish Labour leader Anas Sarwar for the prime minister to resign.
Sarwar this week put his head above the parapet to become the first leading party figure to publicly urge Starmer to quit.
The Scottish Labour leader told a press conference in Glasgow that Starmer had to go in order to boost his party's chances in May's Holyrood election.
He said: "I’m not willing to sacrifice Scotland’s NHS, our schools, our communities, our towns, cities, villages and islands to a third decade of an SNP government.
“That’s why the distraction needs to end and the leadership in Downing Street has to change.
"The opportunity to get rid of a failing SNP government is one that is too important to be missed. We cannot allow the failures at the heart of Downing Street to mean the failures continue here in Scotland.”
His comments come as pressure mounts on Starmer in the wake of revelations that the PM had been warned about Lord Mandelson's ties to disgraced financier Jeffrey Epstein before making him US ambassador.
But while Sarwar was telling the media the PM must resign, Starmer was garnering support from his cabinet ministers.
By last night, almost every minister had posted a message in support of Starmer, including leadership rival Angela Rayner who posted on social media: "I urge all my colleagues to come together, remember our values and put them into practice as a team.
"The prime minister has my full support in leading us to that end."
Meanwhile Starmer told his Labour MPs he would not "walk away", adding: “I’ve won every fight I’ve been in. As I have breath in my body, I’ll be in that fight, on behalf of the country that I love and I believe in.”
It comes after Starmer's chief of staff, Morgan McSweeney, and director of communications, Tim Allan, resigned in the last few days.
And Wes Streeting has been accused or orchastrating a leadership coup after it emerged he held discussions with Sarwar over the weekend before the Scottish Labour leader went public with his call for the PM's resignation, The Telegraph reports.
However, Streeting himself was among the cabinet members to declare public support for Starmer later on Monday.