The EU will seek to resolve its Brexit stand-off with Britain on Wednesday by setting out proposals for a compromise over Northern Ireland.
EU commissioner Maros Sefcovic is expected to give ground in a speech later by signalling that fewer checks will be needed on goods crossing the Irish Sea.
But his proposals may fall short of the demands set out on Tuesday by British negotiator David Frost, who wants EU judges to lose their oversight role.
Mr Frost wants the Northern Ireland Protocol replaced with an entirely new treaty, while the EU insists it will only tinker with the existing deal.
Brussels is not describing its proposals as an ultimatum but believes that negotiations could stretch into next year once they are tabled.
Under the protocol, goods are checked when they move from mainland Britain to Northern Ireland. It means they can then enter the Republic of Ireland, and therefore the EU, without further checks.
The idea is to prevent a hard border in Ireland that could stoke sectarian tensions. But Britain says the checks are excessive and imperilling the 1998 peace agreement in Northern Ireland.
Mr Sefcovic has promised to offer Northern Ireland more of a voice in how post-Brexit trade is managed, after tensions over the protocol led to the fall of the devolved government in April.
The EU commissioner is expected to propose that fewer checks will be necessary on goods entering Northern Ireland.
There are suggestions that the EU could offer reduced checks in exchange for access to UK surveillance databases that would allow monitoring of trade.
Mr Sefcovic has previously indicated that the EU is willing to change legislation to ensure no disruption of medical supplies into Northern Ireland.
But he is unlikely to budge on the issue of the European Court of Justice, which is the final arbitrator under the protocol.
Mr Frost used his speech on Tuesday to call for the ECJ to be replaced by an international arbitrator.
He repeated his threat that Britain could unilaterally suspend the protocol, under a provision known as Article 16 which covers “serious economic, societal or environmental difficulties".
Mr Sefcovic has described the threats as unhelpful and said there were no quick solutions to “an extremely complex situation”.
He has said that Northern Ireland could not remain in the EU’s single market, enabling frictionless trade with the Republic, without oversight from the ECJ.
Brexit tensions hung over a G7 summit in June at which UK Prime Minister Boris Johnson clashed with French President Emmanuel Macron over the deal.
Mr Macron expressed frustration that Britain wanted to renegotiate the protocol less than two years after Mr Johnson signed it.
But Mr Sefcovic appears to have persuaded EU colleagues to seek a compromise with what he said would be a “very far-reaching proposal”.
“I sincerely hope that this will be seen as such by our UK counterparts,” he said last week. He said he hoped for a solution by the start of next year.
Mr Frost said he was ready to discuss the proposals and would “consider them seriously, fully and positively”.
He defended the early renegotiation by telling the EU it had little to lose from changing the protocol.
“For the EU now to say that the protocol — drawn up in extreme haste in a time of great uncertainty — can never be improved upon, when it is so self-evidently causing such significant problems, would be a historic misjudgement,” he said.
“Northern Ireland is not EU territory. It is our responsibility to safeguard peace and prosperity in Northern Ireland, and that may include using Article 16 if necessary.”