Rishi Sunak will battle to save his flagship Rwanda Bill on Wednesday after two senior Tory MPs resigned to form part of a major rebellion.
Lee Anderson and Brendan Clarke-Smith dramatically quit as Conservative Party deputy chairmen on Tuesday night.
They were among 60 right wing Conservative MPs to back controversial amendments to the legislation in a significant blow to the Prime Minister's authority.
MP Jane Stevenson also left her post as a ministerial aide to Kemi Badenoch in the Department for Business for siding with the rebels.
In total 70 MPs, including eight from the DUP, joined the revolt and demanded significant changes that they say will prevent legal challenges to asylum seeker flights taking off to Rwanda.
Centrist Tories have argued the legislation is as strong as it can and it would be "dangerous" for the UK to risk breaking international law and sidelining the European Convention on Human Rights.
The hardliners have insisted they are "prepared" to vote against the Rwanda Bill on Wednesday if a compromise cannot reached overnight.
A group of just 29 rebels would be big enough to overturn Mr Sunak's 56-seat majority.
New Conservatives co-chairman Danny Kruger said he could vote against the Government but hopes Downing Street will continue with "constructive conversations" before the third reading of the Bill on Wednesday.
"I think the size of the rebellion shows that a significant number of Conservative colleagues are serious about amending this Bill," he said.
He conceded it was "painful to break the whip", but added: "I hope the Government will continue the constructive conversations we've had and we will get into a better place tomorrow."
Asked if he could see himself voting against the Bill at third reading, he said: "I am prepared to."
Mr Anderson said he believes "most of the Bill is sound" and it "can work" but he wanted to see a "situation where anyone who arrives illegally in this country has no rights at all to claim asylum".
Former cabinet minister Sir Jacob Rees-Mogg, who voted for the amendments, said the rebellion has not damaged Mr Sunak's position as leader.
Asked what the size of the rebellion says about the PM's position, Sir Jacob said the party is a "democracy" with a "coalition of views", adding: "All party leaders have to deal with that in their own way and Rishi Sunak does that in a courteous and intelligent way."
Tory rebel Sir John Hayes said he would listen to Wednesday's debate and the Government before deciding how to vote on the Bill.
The Conservative former minister said: "The numbers speak for themselves. It was a really impressive number. I think we got a very significant proportion of the backbenchers.
"We've got another day's debate tomorrow, haven't we - so let's listen to that debate and deal with things as they occur rather than before they occur.
"So we will see what the Government says tomorrow."
Downing Street has insisted Mr Sunak still aims to have flights running to Rwanda by the spring, despite plans to draft in more judges to speed up migrant appeals not set to be completed until summer.
Asked whether it was still the plan to revive the stalled scheme by spring, the Prime Minister's official spokesman said: "It is."
Number 10 reiterated that it will "listen if people want to put forward a legal position as relates to their amendments" but that it was working within "specific parameters and one of those is not collapsing the Bill".
