Some 13 former ministers, together with the chairman of the backbench 1922 Committee, Sir Graham Brady, have written to the Prime Minister demanding her not to concede to Labour’s key demand, amid warnings she risks losing the “loyal middle” of the Tory Party if she gives ground on a customs union. The signatories were said to include Gavin Williamson, who she sacked as defence secretary, as well as potential leadership contenders Boris Johnson and Dominic Raab.
A cabinet source said told The Sun: “The talks will end this week whatever. I can’t see Labour carrying on with them.
“Whether she then goes or not will depend on whether No 10 have a Plan B, because we need one now, and it must be credible.”
Their intervention comes as Downing Street sources attempted to “calm Tory troops” by insisting they would not sign up to a permanent customs union.
BBC political editor Laura Kuenssberg tweeted: “No 10 source tries to calm tory troops? ‘We will not sign up to a permanent customs union. We are trying to find a compromise on customs as interim position or stepping stone’.
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“Both sides agree no Parliament can bind future govt + most EU trade deals have a 6-12 mnth exit clause.”
Mrs May is preparing to brief senior ministers on the state of the talks – which began in April – at the weekly meeting of the Cabinet in Downing Street on Tuesday.
Meanwhile the Mrs May’s chief Brexit negotiator, Olly Robbins, is travelling to Brussels for talks with EU officials.
Discussions will include whether the political declaration could be changed – and how quickly – if it allowed the Government and Labour to break the impasse.
The news comes after the two sides’ negotiating teams, led by David Lidington, Mrs May’s de facto deputy, and shadow Brexit secretary Sir Keir Starmer, met again on Monday.
However a group of former ministers, who also include Sir Michael Fallon and Maria Miller, warned Mrs May stands to lose the support of more Tory MPs in the Commons than she gains Labour backers if she breaks her “solemn promise” not to enter a customs union.
The group, who made the point they all backed the Withdrawal Agreement in the last Commons vote in March, said Mrs May could not bind her successor to a deal so any agreement with Labour was likely to be “at best temporary, at worst illusory”.
They wrote: “We believe that a customs union-based deal with Labour will very likely lose the support of Conservative MPs, like us, who backed the Withdrawal Agreement in March … and you would be unlikely to gain as many Labour MPs to compensate.
“More fundamentally, you would have lost the loyal middle of the Conservative Party, split our party and with likely nothing to show for it.
“No leader can bind his or her successor so the deal would likely be at best temporary, at worst illusory,” according to The Times.
Their intervention comes amid growing frustration among Tory MPs, both with Mrs May’s leadership of the party and the continued Brexit deadlock.
Many fear they are heading for a mauling at the hands of Nigel Farage’s Brexit Party in the European elections on May 23 having already suffered heavy losses in the English local council elections earlier in the month.
Following Monday’s talks with Labour, a Number 10 spokesman said they were still trying to find an agreed way forward that would allow Britain to leave the EU with a deal.
He said: “In preparation for an update to Cabinet, today’s meeting took stock across the range of issues discussed in talks over the last few weeks.
“We continue to seek to agree a way forward in order to secure our orderly withdrawal from the EU.”