Sunak is fighting to avoid one clear and mortifying failure... but the clock is ticking for him to save his job - analysis by Olivia Utley

For Sunak, though, this was not the end of the road. Having made the Rwanda policy a central tenet of his premiership, he had little choice but to stick by it and find some sort of workaround.

Three weeks and a lot of meetings later, the Prime Minister has come up with what he hopes is a Goldilocks solution.

WATCH: Brendan Clarke-Smith discusses the Government's deal with Rwanda

Tomorrow, he is putting forward his emergency legislation which would deem Rwanda a “safe country” – but is ambiguous enough to be (he hopes) at least vaguely compatible with both domestic and international human rights laws.

But his backbenchers aren’t happy. Those on the left of the party think that the legislation goes too far: according to Lord Garnier (the former solicitor general) simply declaring Rwanda a safe country when there is no evidence that that’s the case is “political and legal nonsense”.

Meanwhile, MPs on the right of the party are kicking up a fuss too. Today, five groups of parliamentarians held a meeting at which they discussed the viability of the plan.

Their verdict? The bill provides “a partial and incomplete solution to the problem” because although the legislation deems Rwanda safe in general, individual migrants could argue in court that in their personal circumstances, deportation would be dangerous.

Representatives from the groups have stopped just short of saying that they will certainly vote against the Bill tomorrow, but have made it clear that, ideally, they would like to see it pulled altogether.

The Government is hard at work trying to persuade them that although the Bill does allow room for individual challenge, that room is “exceptionally narrow” – ie. Women in the latter stages of pregnancy, for whom flying is unsafe, and those who have complicated illnesses which couldn’t be treated effectively in Rwanda.

But the million-dollar question is: will Conservative MPs believe what the Prime Minister tells them?

The Bill intentionally does not go into forensic detail about the kind of mitigating circumstances a migrant could claim in order to avoid deportation, that is deliberately left up to the courts. So Rishi Sunak can claim all he likes that the wiggle room is “narrow” but MPs will have to take his word for it.

Ultimately there are three possible outcomes to tomorrow’s vote. Either the whips work through the night and manage to persuade a decent number of MPs to back the Bill, in which case the beleaguered PM will live to fight another day. Or the Bill passes, but with a very narrow majority.

This would essentially put the ball into the Lords court. If the Commons looks sufficiently split on the issue, the Lords (which is more left-leaning than the Commons) would feel emboldened to vote it down.

LATEST DEVELOPMENTS:

• Sunak takes incredibly rare action in desperate bid to prevent Tory rebellion
• Sunak's Rwanda plan torn apart in damning THIRTEEN point assessment
• Cameron pulls rank on SNP as Yousaf slapped down for unauthorised meeting with Erdogan

The final outcome, of course, is that the Bill is defeated altogether. If this were to happen, it’s hard to see how Sunak clings on to his job.

The PM said himself that he wanted to be judged on how he delivered on his five pledges, perhaps the most important of which was tackling illegal migration. Failing to pass this flagship legislation would constitute a clear and mortifying failure. The countdown is on…