It comes as ministers prepare to publish a long-awaited white paper on the UK’s future relationship with the EU, revealing the detail of how Mrs May plans trade and customs to work after Brexit.
Amendments lodged by the head of the European Research Group of pro-Brexit backbenchers and supported by MPs including the Scottish Conservative Ross Thomson would block the government from keeping one foot in the EU customs union for goods, and prevent a proposed ‘backstop’ solution for the Irish border from creating an internal trade boundary in the Irish Sea.
The amendments are unlikely to pass, but will send a message to government whips amid claims that more ministers could follow Boris Johnson and David Davis in resigning over Mrs May’s plan.
Meanwhile, it was revealed that government preparations for a possible no-deal Brexit include stockpiling processed food in case shipments are held up at the border.
In a even more dramatic contingency plan, reports suggest the government is preparing to airlift electric generators from military bases in Afghanistan and float them on barges around the Northern Irish coast if electricity supplies from the Republic are cut off.
In his first parliamentary duties since being appointed to replace Mr Davis as Brexit Secretary, Dominic Raab will insist the White Paper “respects the result of the referendum, and delivers a principled and practical Brexit.”
Unveiling the 120-page document, Mr Raab is expected to tell MPs: “This is the right approach - for both the UK and for the EU. The White Paper sets out in detail how it would work.”
On Tuesday night, Conservative MP Andrea Jenkyns, said it was time to “put country first” and warned the Prime Minister that “there will no doubt be more resignations from Brexiteers in the Cabinet” if further concessions were made to the EU.
In another sign of the deepening rift in the Conservative Party, Stewart Jackson, Mr Davis’ former special adviser at the Brexit department, claimed Number 10 had blocked his reappointment.
Asked at the Nato summit in Brussels yesterday if she expected more resignations from the government, Mrs May insisted that her plan delivered on the Brexit “red lines” she has set out.
“It delivers on the vote that people gave on Brexit, it delivers the fact that we will have an end to free movement, we will have an end to the jurisdiction of the European Court of Justice in the UK, we won’t be sending vast contributions to the EU every year, we’ll be out of the Common Agricultural Policy, out of the Common Fisheries Policy,” she said.
“We deliver that Brexit and we do it in a way that protects jobs and livelihoods and meets our commitment to Northern Ireland.”
Meanwhile, the SNP demanded a seasonal agricultural workers programme to replace dwindling numbers of EU fruit-pickers amid reports that tonnes of soft fruit has been left to rot by Scottish producers in recent weeks. Angus South MSP Graeme Dey said the losses were having a “hugely damaging impact upon the local economy”.