The Tories are on the brink of a historic split, senior Conservatives have warned, as Brexiteers and Remainers both threatened to torpedo the Government if they did not get their way on Brexit.

Pro-EU MPs claimed a third of the Cabinet would resign if Theresa May pursued a no-deal Brexit in the face of almost certain defeat over her deal, as they threatened a walkout of backbenchers that would obliterate the Government’s Commons majority.

At the same time, The Telegraph understands that several senior ministers are agitating Mrs May to immediately open talks with Labour MPs about a compromise involving a permanent customs union if her deal is defeated by a large margin on Tuesday.

One senior Tory said: “A growing number of the Cabinet now think the only feasible option is to tack towards a softer Brexit involving a permanent customs union, in order to get a deal through with Labour votes. Amber [Rudd], David [Gauke], Greg Clark and others have made noises along those lines.”

Steve Baker, the deputy chairman of the European Research Group of Eurosceptics, warned that the move would risk a split akin to the schism prompted by Robert Peel’s repeal of the corn laws. “It’s difficult to see how at least some Conservative MPs would not withdraw confidence in the Government,” he said.