Theresa May has abandoned her pledge that a deal to keep the UK in the EU customs territory must be “time-limited”, paving the way for likely cabinet resignations.
The prime minister’s spokeswoman refused – four times – to say the “backstop” agreement, to avoid a hard border in Ireland, would have a strict end date, the assurance she set out four months ago.
Instead, No 10 said only that it must be “temporary”, a much looser word that - pro-Brexit ministers fear – will leave the UK locked into an effective customs union for many years to come.
Asked if the reworked customs proposals, being negotiated in Brussels, would have “an end date”, Ms May’s spokeswoman said only that it “would be temporary”.
She attempted to head off a backlash by adding: “The prime minister would never agree to a deal which could trap the UK in a backstop permanently.”
However, the U-turn was quickly attacked by Steve Baker, a leading Brexiteer Tory, who said it risked “effectively committing the UK to membership of the single market and customs union”.
“That won’t wash. The British people voted to take back control over money, laws borders and trade,” the former Brexit minister said.
“On many occasions both the PM and the Brexit Secretary said the backstop would be time limited. This is critical,” he tweeted.
At a briefing for journalists, the spokeswoman insisted the UK would insist that the backstop “needs to” end no later than December 2021.
However, without a legal requirement for that to happen, in the Brexit withdrawal deal, it would depend on the EU agreeing later that as-yet unproven technology has produced a solution.
If it refused, the Irish backstop would then lock the entire UK permanently into an effective customs union, unable to sign its own trade deals, many Tories fear.
Other cabinet ministers believed to be prepared to resign include Esther McVey, the work and pensions secretary, Penny Mordaunt, the international development secretary and even Liam Fox, the international trade secretary.
There are also doubts over the future of Brexit secretary Dominic Raab, who has repeatedly said publicly that the customs union plan must be time-limited.
Asked if Ms May feared cabinet walkouts, the spokesman said: “The prime minister is focused on getting the best possible deal and that’s what she is working to deliver.”
And she insisted: “Our position is that this future economic relationship needs to be in place by the end of December 2021 at the latest.”
Andrew Bridgen, another Brexiteer Tory, urged fellow MPs to act by sparking a vote of confidence in the prime minister’s leadership.
“They should put the letters in and test the prime minister’s popularity with the party,” he told the BBC.
Mr Bridgen said Tory MPs had been “holding back”, but that the situation would change “if it becomes clear that we are stopping in a customs union”, adding: “It’s coming to a head this week.”
The government is believed to be pushing for a “review clause” to bring an end to the backstop, but its legal strength is unclear.