The emergency Rwanda legislation which could determine whether Rishi Sunak remains Prime Minister is “weak” and “will not work”, his former immigration minister has said.

Robert Jenrick, who quit last week over the Bill, said he would not support it in a crunch vote in the Commons, although he suggested it could yet be fixed at a later date.

Mr Sunak faces a brutal week starting with the Covid-19 Inquiry asking him about the ‘Eat out to help out’ scheme he promoted as Chancellor amid fears it could spread the virus.

On Tuesday, MPs have their first vote on his Safety of Rwanda Bill, which is intended to declare the African country a safe destination to which the UK can deport asylum seekers.

The legislation is intended to get around the UK Supreme Court’s objection to the current Rwanda scheme, which was ruled unlawful last month.

Expected to cost taxpayers £290m by the end of next year, the plan has yet to result in a single asylum seeker being sent from the UK to Rwanda to have their claim processed.

Mr Sunak has said the plan is critical to deterring illegal boat crossings on the Channel, and promised flights will take off next year.

However he faces a twin at the Bill’s second reading on Tuesday, with both moderate and right-wing groups of Tory MPs objecting to it as either too hard or too soft.

The PM and Foreign Secretary Lord Cameron have engaged over the weekend with both sides, who are due to meet at parliament on Monday to discuss how to vote.

The last time a Bill fell at such an early stage was in 1986, and defeat could finish Mr Sunak.

The moderate One Nation group is concerned about the Bill’s legal impact and the idea of ordering the courts to deem Rwanda a “safe” country rather than use their own judgment.

Meanwhile the European Research Group and others on the right believe the Bill does not go far enough in pushing the envelope on international law.

Even if Bill declared Rwanda safe  in general, thouands of asylum seekers might still be able to claim in court that they were specifically at risk.

Cabinet Secretary Michael Gove downplayed the prospect of that happening, but accepted it might in some cases and refused to say how many.

The veteran Tory MP Sir Bill Cash, who chaired a “star chamber” of lawyers looking at the Bill, said on Sunday it was not “sufficiently watertight”, but hinted it could be amended.

Mr Sunak has told his MPs the Conservatives must “unite or die”, but only 28 rebels are needed to wipe out his majority as the Opposition parties will oppose the Bill. 

Miriam Cates and Danny Kruger, co-founders of the right-wing New Conservatives group, said there are “big question marks” over the legislation, writing in the Sun on Sunday: 

“There’s no point uniting around a policy that doesn’t work. That way we’ll just unite and die.” 

Amid speculation that Mr Sunak could face a confidence vote, Mr Jenrick, a close ally of former Home Secretary Suella Braverman, said he was “not interested” in replacing him.

The Newark MP told the BBC’s Sunday with Laura Kuenssberg show:  “I want the Conservative Party to win the next general election. I want it to make good on its manifesto commitments. I think there is a way to do that.”

Asked if he would vote for the Rwanda Bill on Tuesday, he said: “No, I won’t be supporting this Bill, but I do think we can fix this, and that’s what I want to do now.

“I care about this policy because I care about border security and I’m determined that we can persuade the Government and colleagues in Parliament that there is a better way.

“We’ve already done two Bills, this is the third Bill. It’s three strikes or you’re out.

“I want this Bill to work and create that powerful deterrent and I’m afraid it’s very clear to all those people who really understand how this system operates that this Bill will not succeed.”

He said “a political choice has been made to bring forward a Bill which doesn’t do the job”.

He went on: “The test for this is not ‘Can you get one or two symbolic flights off before the next election with a handful of illegal migrants on them?’, it’s ‘Can you create a strong deterrent that is sustainable and stops the boats and protects the borders of this country for years to come?’ That’s what I want to achieve and I’m afraid this Bill is not it.”

He said Tory electoral prospects “hinge, in good measure” on addressing high levels of legal migration and asylum claims, warning failure would result in “the red-hot fury of the public”.

Senior moderate Tory Damian Green said only “a vanishingly small number” of Tory MPs wanted to change the PM, and they were “either mad or malicious or both”.

Cabinet Secretary Michael Gove later insisted the Rwanda Bill was “tough and robust” and “legally sound” despite the concern of other Tory MPs that it was not fit for purpose.

He told Sky’s Sunday Morning With Trevor Phillips: “We take seriously the views of colleagues, particularly eminent colleagues like Sir Bill [Cash] who have deep and profound legal experience. But we believe this Bill is tough and robust.”

However he also signalled a willingness to consider amendments, telling Times Radio: “As it goes through its various stages we will consider thoughtful suggestions about how the legislation can be improved.”

He said the Government was “not contemplating” calling the election if the Bill fell.

Sir Keir Starmer will use a speech on Tuesday to accuse the Tories of being unable to govern while their warring factions are “fighting like rats in a sack”.