The prime minister faces a walkout if she whips her MPs either for or against crashing out of the EU.
Now the foreign secretary has revealed she is weighing up a free vote on whether to rule out no-deal Brexit – despite inevitable criticism that it would expose her as too weak to impose a collective policy on such a crucial issue.
“That’s something the government has to make a decision on, the prime minister has to make a decision on,” Mr Hunt said. “I don’t think a decision has been taken.”
During an interview, Mr Hunt also confirmed the government could now settle for an “arbitration mechanism” to escape the Irish backstop – rather than demanding a time limit, or strict exit clause.
And he acknowledged an uphill struggle to win the crucial “meaningful vote” next Tuesday, saying: “It isn’t certain – that’s why we have got a lot of work to do.”
The comments came as Geoffrey Cox, the attorney general, and Stephen Barclay, the Brexit secretary, headed to Brussels for talks over the backstop, an insurance policy to avoid a hard border in Ireland.
Ms May is pinning her hopes of passing her deal on Mr Cox changing his legal advice that the UK is in danger of being trapped in the backstop – and therefore the EU customs union – indefinitely.
However, the EU has ruled out a time limit or unilateral exit mechanism, forcing the UK to fall back on a much weaker arbitration system.
Brexiteer Tories are demanding the party is whipped to support a no-deal departure if necessary, claiming the support of two cabinet ministers.
“It is crystal clear that the government has to keep no deal on the table and whip against an extension [of Article 50],” former leader Iain Duncan Smith told The Daily Telegraph.
However, that would almost certainly trigger the resignations of Amber Rudd, the work and pensions secretary, David Gauke, the justice secretary, and Greg Clark, the business secretary – who forced Ms May to concede a parliamentary veto on a no-deal Brexit last week.
Speaking to BBC Radio 4, Mr Hunt also softened his previous claim that Britain would thrive after a crash-out Brexit, conceding it “would cause huge disruption”.
And, declining to say the UK was still pushing for a time limit to the backstop, he said: “What we are saying to the EU is that the crucial thing is that, as a sovereign parliament, it must not be possible to trap us in the EU customs union indefinitely.
“How we get there is something we are prepared to be flexible about.”
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies