Cabinet set for showdown on key Brexit policy amid tensions between Theresa May and David Davis

'Backstop' option for Northern Ireland border is still to be agreed by senior ministers, Brexit secretary admits

Senior ministers are set for a showdown on the UK’s future relationship with the EU after it emerged that a key element of the plan has still not been agreed by the cabinet.

Plans for a “backstop” customs option were due to be published on Thursday but could be delayed amid a row between Theresa May and David Davis, the Brexit secretary.

Appearing to confirm that there remain major divisions within the cabinet, Mr Davis admitted the proposal would only be published once ministers have agreed on it.

The row centres on how to manage the Northern Ireland border – one of the most contentious areas of Brexit negotiations. The backstop option, agreed in principle by the cabinet last month, would see the UK remain in part of the EU customs union if no other option for avoiding a hard border is found.

Brexiteers fear the plan could result in the UK remaining in the customs union indefinitely, and have insisted on a strict, legally binding time limit, as well as the option for the UK to unilaterally withdraw from the arrangement.

The Downing Street proposal, however, is believed to include only a vaguer promise that the backstop will be time limited, leading to strong opposition from Eurosceptic ministers, led by Mr Davis.

Answering questions after a speech on security cooperation on Wednesday, the Brexit secretary confirmed the plan had still not been signed off by ministers.

Asked if the proposal would be published on Thursday, as reports suggest, he said: “It’s for a cabinet committee to decide that. If they conclude then you’ll see it tomorrow, but it’s up to them to decide.”

He added: “The detail of this is being discussed at the moment. it’s been through one cabinet committee, it’s going to another and it would be improper of me to pre-empt the negotiations there, but I suspect it will be fairly decisive.”

Some reports had suggested Mr Davis was considering resigning over disagreements with Ms May on the matter.

Asked if he would be able to stay in his job if the backstop proposal was published without his approval, the Brexit secretary said: “That’s a question, I think, for the prime minister, to be honest.”

He also insisted there would be a time limit on the backstop option, saying: “The prime minister has already made public the fact that we expect to put a time limit on the backstop proposal.”

The government is under mounting pressure to publish details of its Brexit plans ahead of crunch votes on its flagship EU (Withdrawal) Bill next week and a European Council meeting in three weeks’ time.

The UK needs to ensure sufficient progress has been made on sticking points such as the Northern Irish border in order to allow talks to progress to the matter of a UK-EU trade deal.