Lee Anderson could deal Rishi Sunak a blow by backing the Tory right’s amendments to his Rwanda plans in crunch votes this week.
Sources in the rebel camp said the Tory deputy chairman has told colleagues he intends to defy the Government as Conservative divisions are set to be dragged back into the open.
The amendments to the Rwanda Bill, which will return to the Commons on Tuesday, have received the backing of more than 50 Tory MPs.
But any attempt by the Prime Minister to placate them would be met by opposition from Tory moderates.
Amendments tabled by Robert Jenrick, who resigned as immigration minister over the legislation, and veteran Tory Sir Bill Cash have been gaining support.
They are seeking to disapply international law from the Bill and curtail asylum seekers’ rights to appeal against flights to Kigali under the key policy to “stop the boats”.
Mr Anderson has not commented publicly, but rebel sources said they had been told he will back the amendments brought by Sir Bill and Mr Jenrick if they are selected.
The amendments are unlikely to pass as they will not get Labour support, but the real test will come at the third reading when rebels may vote against the Bill entirely.
Three leaders of groups on the Tory right, Mark Francois, Sir John Hayes and Danny Kruger, have said they would oppose it if Mr Sunak does not bow to their demands.
The former home secretary and rival to Mr Sunak, Suella Braverman, has said she will this time vote against the Bill if there are “no improvements”, having previously abstained.
If rebels were successful, blocking the Prime Minister’s flagship Bill would trigger fresh chaos – something that may make opponents toe the line to let it pass.
Former justice secretary Sir Robert Buckland has said he would not back the Bill if the changes are made.
He told BBC Radio 4’s The World This Weekend: “I’m going to consider the position very carefully to see what I do at third reading.
“I can say this, if any of the amendments that are promoted by some other colleagues pass then there’s no way I can vote for this Bill at third reading.
“I think already we are pushing the edges of comity – that is that mutual respect between Parliament and the courts – very, very aggressively indeed.”
Mr Sunak himself has argued that moving a further “inch” on the Bill would risk the Rwandans quitting the deal.