The president of the EU Commission Jean-Claude Juncker will host British Prime Minister Theresa May on Wednesday for talks on the Brexit crisis.

Juncker’s spokesman Margaritis Schinas told reporters that the pair would meet at the European Union’s headquarters at 6:30pm (1730 GMT).

The news Tuesday came a day after Britain’s minister for Brexit talks Stephen Barclay and Attorney General Geoffrey Cox met EU negotiator Michel Barnier.

Barclay’s office said they had “held a productive meeting… on resolving the outstanding issue of the backstop,” holding up a divorce deal.

The backstop is a clause in the withdrawal arrangement that keeps Britain in the EU customs union until a way is found to ensure there is no return to a hard border between Northern Ireland and Ireland.

May hopes that if Cox is able to tell British MPs that the backstop would not be permanent under an updated deal it might pass a sceptical House of Commons.

But the EU spokesman reiterated that the other 27 EU member states will not renegotiate the divorce accord, which they signed with May in November.

“We cannot accept a time limit to the backstop or a unilateral exit clause,” Schinas said.

“Further talks will be held within the week to see whether a way through can be found that would gain the broadest possible support in the UK parliament and respect the guidelines of the 27,” he said.