Beleaguered Jeremy Corbyn is facing the prospect of most of his MPs voting to oust him as Labour's bitter civil war threatens to tear the party apart.
Furious Labour MPs told the leader to his face that he must quit for the good of the party at a heated meeting in parliament on Monday night.
But a defiant Mr Corbyn is refusing to bow to "a corridor coup" despite losing around 40 members of his front bench team in just two days.
MPs will vote on the no-confidence motion in a secret ballot that, while not binding, will heap further pressure on the Islington North MP.
Mr Corbyn's aides said critics wanting to remove him from the top job would have to launch a formal challenge. They are confident he would see off the treat, believing he retains the backing of the grassroots activists who swept him to victory in 2015.
Significant numbers of supporters turned out to show solidarity for the embattled leader at a rally in Parliament Square.
Mr Corbyn appealed for "unity" and told the crowd: "Don't let the people who wish us ill divide us."
But at a brutal meeting of the Parliamentary Labour Party the Opposition leader was told he was not up to the job and urged to "do the decent thing".
The Labour-supporting Daily Mirror joined the calls for him to quit for the sake of his party and country.
It said filling dozens of vacancies with "inexperienced lightweights" was like "using a toothpick to prop up a collapsing skyscraper" and suggested Mr Corbyn's attempts at "clinging to power increasingly looks like an act of vanity".
"A beleaguered Jeremy Corbyn should take a long hard look in the mirror, then do what is in the best interests of his party, working people and the country because, to be frank, it is increasingly hard to imagine him as a Labour prime minister on the steps of Downing Street," it adds.
The Opposition leader will continue to make appointments to his front bench team although it is unclear if every position will be filled.
Among the most senior figures to quit in Monday's wave of resignations was Angela Eagle, who, as shadow first secretary of state, deputised for the leader at Prime Minister's Questions.
The former shadow business secretary is among those tipped as a possible challenger to take on Mr Corbyn.