EU and UK officials have resumed Brexit talks in the hope of reaching a deal that can be agreed by leaders at a key summit on Thursday.
Prime Minister Boris Johnson is expected to update the cabinet on the progress of the negotiations, which continued into the early hours.
On Tuesday, there were reports a deal was imminent, amid claims the UK had made concessions over the Irish border.
No 10 said talks were “constructive” and progress was being made.
The EU’s chief negotiator, Michel Barnier, will update the bloc on the state of the negotiations later when he briefs EU commissioners and ambassadors.
Mr Johnson is facing a race against the clock to reach a new Brexit deal before the two-day gathering of EU leaders.
Any deal will need to be published – along with a legal text – if the EU27 are to consider ratifying the withdrawal agreement at their summit.
That meeting is crucial because under legislation passed last month – the Benn Act – Mr Johnson is compelled to ask the bloc for a delay to Brexit if he does not get a new deal approved by MPs by Saturday.
The UK is due to leave the EU at 23:00 GMT on 31 October and the prime minister has repeatedly insisted he will not request a delay.
But in addition to the challenges of reaching an agreement with the EU this week, Mr Johnson also requires support from Conservative Brexiteers and Democratic Unionists if he is likely to get his deal through Parliament.
Such support rests on the UK’s proposed alternative to the Irish backstop – the measure aimed at preventing a hard border on the island of Ireland.
On Tuesday evening, meetings were held at Downing Street with backbench MPs and leaders of the DUP.
After a 90-minute meeting with the prime minister, the DUP said “it would be fair to indicate gaps remain and further work is required”.
Earlier in the day, the party’s leader, Arlene Foster, said she could not accept reported plans of a customs border in the Irish Sea – meaning Northern Ireland would be treated differently from the rest of the UK.
Former Brexit Secretary David Davis said the support of Tory eurosceptics could not be taken for granted and MPs would subject any agreement to “two or three key tests” – including whether it compromised the future of the United Kingdom.
“Quite a lot of Tory MPs will take their line from what the DUP say,” he told BBC Radio 4’s Today. “If the DUP say this is intolerable, that will be quite important.”
Former Northern Ireland secretary Owen Paterson has already expressed unease about reports of what could be in the agreement, telling the Sun that a customs border down the Irish Sea would be “unacceptable”.
But Iain Duncan Smith, another Brexiteer and former Conservative party leader, said there was a “genuine strong sense of goodwill” towards the prime minister’s efforts.
Most of his party – “bar a small core” – wanted to get a deal and he suspected they would want to back it, he told BBC Breakfast.
He denied reports in the Sun newspaper that he “exploded” at Downing Street officials during Tuesday’s meeting, saying he was in fact rushing to get on the London Underground to get back to his constituency.
News from BBC