Cabinet ministers are gathering in Downing Street to hear about Theresa May’s latest attempts to find a Brexit deal.
The main sticking point is how to guarantee no new checks on goods at the Irish border.
Mrs May needs to unite her cabinet behind her position before trying to reach agreement with the EU.
The EU’s chief negotiator said there had not yet been enough progress to call a special summit.
Michel Barnier told a Belgian broadcaster that the Irish border remained the main hurdle to be overcome. If enough progress is made, he said, he will recommend a summit is convened to finalise the deal.
But there needs to be time for the UK and EU Parliaments to ratify whatever is agreed before the UK leaves in March.
The withdrawal deal is said to be 95% complete.
But the tricky bit is proving to be how to honour the commitment by both sides to guarantee no new hard border in Ireland.
There is disagreement on whether this “backstop” should apply to Northern Ireland, or the whole of the UK – and on whether it should be time-limited or revoked by the UK.
It is an issue because after Brexit it will become the UK’s land border with the rest of the EU, which has a single market and customs union so products do not need to be checked when they pass between member states.
And there have been warnings that a hard border would undermine the peace process in Northern Ireland.
Environment Secretary and Brexiteer Michael Gove said he was “sure the prime minister will be making progress” as he set off for the cabinet meeting.
Analysis by BBC political editor Laura Kuenssberg
Cabinet is not expected to be a meeting where a final decision is made, even though some people around government would like it to be.
There is real suspicion on the Brexiteer side that the PM will, at some point, try to bounce them into a decision without much discussion beforehand.
But on the other side, some former Remain voices think Theresa May should call the bluff of those who are making it hard.
In a sign that the former Remainers in the Cabinet are starting to present their own pushier front, Chancellor Philip Hammond, the PM’s second-in-command David Lidington and Business Secretary Greg Clark met on Monday night ahead of the get-together.