'Stop the boats' pledge has become a threat to Rishi Sunak as his party divides over the Rwanda Bill

Rishi Sunak has boasted it is the toughest immigration law ever.

But the Rwanda Bill, produced after the Supreme Court ruled his plan to deport asylum seekers to the East African country was unlawful, is now seen as an "existential threat" to the prime minister because some in his party think it's not tough enough.

The court ruled against the UK Government because it found Rwanda was an unsafe country for asylum seekers. The government says the Bill "addresses the concerns of the Supreme Court". What it actually does is tell the courts to ignore the concerns. It lays down that, regardless of the facts on the ground, Rwanda must be treated in future as if it were a safe country.

Rishi Sunak has made his 'stop the boats' pledge a defining issue of his premiership - but the Rwanda policy, designed to halt the Channel crossings, has become a cause of division. Picture: Gareth Fuller/PA Wire.

And the Bill goes further, telling the courts that human rights laws must not be considered in relation to Rwanda. It effectively seeks to ban the courts from finding against the government in any future cases over deportations to Rwanda.

Yet even this is not enough to satisfy the most rabid right-wingers in the Tory party, who say a clause allowing individuals to appeal if there are "compelling evidence relating specifically to a person's individual circumstances" means the law is not watertight.

Dramatically, the immigration minister Robert Jenrick – previously seen as a loyal ally of Mr Sunak – resigned, arguing the Bill did not go far enough. And former Home Secretary Suella Braverman says it won’t work.

Mr Sunak’s reply is that if the UK went any further, the plans would collapse because Rwanda has made it clear it would not take part in a scheme which led to the UK breaching its obligations under international law. That a de facto one-party state is taking a stronger position on the importance of observing international obligations than the UK is a damning indictment of this policy and the Conservative party which has always proclaimed the rule of law as a founding principle.

It looks like Mr Sunak will get the Bill through a Commons vote tomorrow (Tuesday, December 12), but only because the rebels are keeping their powder dry for the more detailed consideration of the legislation at a later stage, when he could well be defeated. And that would be another blow for a prime minister desperately trying to rescue his party’s poll ratings ahead of a general election.

Home Secretary James Cleverly has said the Rwanda policy is not the be all and end all of the government’s approach to immigration – but the prime minister has made his "stop the boats" pledge a defining issue of his premiership, even though the refugees arriving here via the dangerous Channel crossings make up a tiny proportion of the UK’s record immigration figures.

Immigration will almost certainly be made a key election issue and the Rwanda plan will inevitably be a prominent part of the debate. Most voters are more concerned about the cost of living crisis and the NHS, but immigration is an issue which preoccupies many of those who voted for the Tories in 2019.

The prime minister saw his promise to "stop the boats" as a vote-winner when he announced it, but now it is causing major divisions among his MPs – and divided parties don't win elections.