Prime Minister Theresa May’s government is preparing to publish its plan to keep the U.K. under European Union customs rules for longer as it seeks to break the Brexit deadlock, people familiar with the matter said.

British negotiators expect to send the EU a document this week setting out how May imagines a time-limited extension to existing customs arrangements would work, two people said, speaking on condition of anonymity.

Brexit talks are stalled over the thorny question of how to avoid a hard border between the U.K. and Ireland. Negotiations are due to start again in Brussels this week, with the clock ticking down to a crunch summit of EU leaders starting on June 28.

May’s customs backstop plan would allow goods to cross the Irish border without checks, the people said, though the document setting it out still needs to be signed off by senior U.K. government officials before it’s published.

One person said the backstop paper would emphasize the need for a strict time limit on any extension of the U.K.’s membership of the EU’s tariff regime. May’s inner Brexit cabinet agreed the broad outline of the plan last month.

EU officials have been dismissive of the British plan for the Irish border “backstop.” But the U.K. hopes that putting its plan down on paper will convince the EU to engage more seriously with the idea, the people said.