The European Union will set out its plan aimed at resolving a row with the UK over the Northern Ireland Protocol later.
The measure, set up to avoid a hard Irish border, has meant a trade barrier down the Irish Sea and has angered unionists in the North.
The EU is expected to outline changes to how it operates, following a speech in which the UK's Brexit minister called for changes to the post-Brexit arrangements.
European Commission Vice-President Maroš Šefčovič will speak a day after Britain's Brexit Minister David Frost claimed a "new" protocol needed to be thrashed out between Brussels and London.
He claimed the current arrangements are "not working".
In a speech in Lisbon on Tuesday, Mr Frost accused the EU of being an organisation "that doesn't always look like" it wants the UK to succeed.
He also called for the removal of the European Court of Justice (ECJ) from oversight of the protocol.
This is something that Foreign Affairs Minister Simon Coveney has said creates a new "red line" barrier to progress.
He also claimed this is an issue that London knows the EU "can't move on".
Tánaiste Leo Varadkar has also warned the UK's requests would be "very hard to accept" in Brussels.
"The role of the European Court of Justice is there to adjudicate the rules of the single market," he says.
"I don't think we could ever have a situation where another court could decide what the rules of the single market are."
And Fine Gael's spokesperson on European Affairs, Neale Richmond, says he is concerned the deadlock will not be broken.
"I'm very worried at this stage, to be quite honest, based on the speech made by Lord Frost in Lisbon - where he effectively said he wanted to scrap the protocol and draw up something completely new.
"This has come just in advance of the European Commission presenting a very generous package that's been based on months of engagement with civic, community and business leaders in Northern Ireland - as well as with British government officials.
"Hopefully what the British government do is they take what has been proposed by the European Commission seriously - they study it, they acknowledge that it is very generous and that seeks to achieve a much easier situation for the people and businesses in Northern Ireland.
"But based on the rhetoric that we've had over the last couple of weeks from the British government, I'm not very optimistic".
Ahead of Mr Šefčovič's speech, another senior European Commission figure expressed hope that the EU's proposals would be met with a positive reception.
Frans Timmermans, a fellow European Commission vice-president to Mr Šefčovič, says: "We just want to find practical solutions for the problems of the people and businesses of Northern Ireland.
"And we'll be in that mode tomorrow when we discuss it in the College of Commissioners and we will continue to follow that line.
"We know that there are some objective difficulties in Northern Ireland for citizens and businesses and we want to be part of solving those and we will make some practical propositions to solve them.
"Let's try and find practical solutions to this and let's not try and politicise it too much."
Asked about any potential triggering of Article 16 by the UK that would suspend the protocol, Mr Timmermans adds: "That's up to them to do, that's what they could do if they want to, but our focus is on finding solutions.
"How do you help the people in Northern Ireland and the businesses in Northern Ireland by triggering Article 16?
"Why not just try and find practical solutions? We will make some propositions tomorrow and hopefully they will be met with a positive reaction from the British side."
Additional reporting: IRN