Remainers led by Stephen Hammond and Nicky Morgan will be pushing a new amendment to the government's trade bill, which will make it a negotiating objective to "participate after exit day in a customs union with the EU", in the event that a deal on frictionless trade can not be secured by January. May's spokesman said there would be no second referendum under any circumstances, and restated her position that the Chequers plan was the only way to deliver a Brexit that worked in the best interests of the country.
May said the plan outlined in the white paper honours the wishes of British voters - who in June 2016 backed Brexit with 52 per cent of the vote - while protecting industry and national security.
But they prompted a total of eight resignations, including that of Brexit secretary David Davis and foreign secretary Boris Johnson, and a growing threat to the prime minister. That's the question everyone in Westminster is asking this morning as the key piece of Brexit legislation returns to the Commons for its remaining stages before going to the Lords.
However, the government did suffer an unexpected defeat on a separate amendment, which means it will now be required to seek an agreement that allows Britain to have continued participation in the European medicines regulatory framework.
"Some people are saying they want to vote in the trade bill to keep us in the customs union".
Her government on Monday avoided a humiliating defeat in Parliament when it narrowly won another vote over her Brexit customs bill - but only after reluctantly accepting amendments put forward by Brexit hardliners.
"We have accepted these amendments because we believe them to be consistent with the approach that was set out and agreed at Chequers", he said.
A senior Government minister arriving at the Commons to vote on the trade bill was in a filthy mood.
Her recent white paper outlining plans for a common rule book with the European Union over trade in goods has infuriated those who favour a complete break even if it risks causing an economic shock.
Scott Mann, Conservative MP for North Cornwall, wrote to Prime Minister Theresa May to tender his resignation on Monday morning.
The commission has already put together a task force to prepare the member states for the consequences for a possible no deal.
British lawmakers passed the Taxation (Cross-Border Trade) Bill Monday that creates an independent customs policy for Britain after it leaves the European Union.
Remainer conservative MPs warned that the Brexit plan amended by hardliners increase the likelihood of a no-deal divorce, and that prospect is becoming more tangible in Brussels as well.