His comments suggest that the DUP could seek to collapse Stormont by February if the UK and EU have not managed to secure an agreement on reducing customs checks on goods from Great Britain to the province.

While campaigning for Northern Ireland Assembly elections will effectively commence from March, it also opens up the prospect of Stormont being suspended earlier than anticipated.

Downing Street and the Irish Government have also pointed to the end of February as an informal cut-off point for the talks, fearing any further delay could see the issue dominate the assembly elections.

But Sir Jeffrey’s calls are likely to be seen as unhelpful in Whitehall, as the Government has so far sought to avoid getting hard deadlines for the talks in order to provide negotiators with sufficient breathing space.

While he initially issued his threat to pull out of Stormont and force an early election in September, this was paused when the negotiations over the protocol began in order to help strengthen Lord Frost’s hand.

France will not use EU presidency to push harder line in talks

His intervention comes soon after Lord Frost quit the Cabinet, citing unease at the “direction of travel” in the Government.

While the former Brexit minister has insisted he and Boris Johnson remained united on the protocol negotiations, it is understood he was privately frustrated at progress in the talks.

The UK has also dropped its demands for an immediate removal of the European Court of Justice’s oversight of EU rules which continue to apply in Northern Ireland, despite it being one of Lord Frost’s key priorities heading into the negotiations.

Meanwhile, in a boost for Ms Truss, EU diplomats told The Telegraph that France will not use its EU presidency to push a harder line in negotiations over the Northern Ireland Protocol.

There had been fears that Emmanuel Macron, the French president, could attempt to use the position to increase pressure on the UK amid an ongoing dispute over post-Brexit fishing rights.

“I’m afraid it’s not going to be the French presidency messing up discussions over the protocol,” one diplomat said. “From where we sit, the tone quality and outcome of the talks more than anything depend on the mood of two people – Johnson and Truss.”