The EU is ready to extend Brexit’s post-divorce transition period by a year to allow more time to find a trade deal, diplomats said Wednesday ahead of a difficult summit.

Talks are at an impasse over the issue of a legal backstop to keep the border between Northern Ireland and the Irish Republic open after the UK leaves the bloc on March 29 – but EU negotiator Michel Barnier has an idea.

According to two European diplomats, Barnier is ready to add a year to the 21-month post Brexit transition period – taking it to the end of 2021 – to provide more space to strike a trade deal.

This offer would not in itself resolve the back-stop issue, which must be settled in the Brexit treaty that must be ratified before March to avoid a damaging “no deal” scenario.

But the extension would grant more time to agree a new EU-UK trade relationship and avoid the need for separate plans for Northern Ireland, which London staunchly opposes.

The diplomats said that Barnier had revealed his offer to EU ministers at a meeting in Luxembourg on Wednesday.

With the offer on the table, Europe is seeking to put pressure on May to come to Brussels with ideas of her own.

“I am going to ask Prime Minister May whether she has concrete proposals on how to break the impasse,” EU President Donald Tusk declared.

But May, hemmed in by opponents in her own party and even in her own cabinet, has no such proposals.

Previously, both sides had agreed that Britain crashing out of the Union on March 29 next year with neither a divorce agreement to future ties would be an economic and diplomatic disaster.

But, after Britain’s refusal to accept an indefinite legal “backstop” to prevent the return of a hard border between Northern Ireland and the Irish Republic, doubts are mounting.

Back in Brussels, a stern Tusk said he had “no grounds for optimism” based on a report Tuesday from Barnier and May’s appearance in parliament on Monday.

The main disagreement between London and Brussels is over how to keep the Irish border open after Brexit, but May is also fighting with her own MPs, who must ultimately approve the final divorce deal.

At a three-hour cabinet meeting on Tuesday morning, which included ministers with reservations about her strategy, May said a deal was possible if they all stood together.

“I’m convinced that if we as a government stand together and stand firm, we can achieve this,” she said, according to her spokesman.

Addressing MPs in the House of Commons on Monday, May had said a deal was “achievable” while sticking to her principles on the Irish border issue.

To solve the Irish question, Britain has proposed staying aligned to the EU’s customs rules until a wider trade deal can be signed that avoids the need for any frontier checks.

May said the EU was also insisting on its own “backstop” in case the London proposal did not work, which would see Northern Ireland alone stay aligned to the customs union and single market.

She says this would threaten the integrity of the United Kingdom – and it is strongly opposed by her Northern Irish allies from the Democratic Unionist Party (DUP).