Speculation is mounting that a Brexit deal will be unveiled on Monday - with a summit to seal the agreement at the end of the month.
The EU commission is said to be planning for negotiations to conclude within days, despite bitter wrangling within the Cabinet over Irish border concessions.
Foreign Secretary Jeremy Hunt has also insisted he is confident a package will be finalised over the next three weeks, potentially coinciding with the November 25 summit date circulating in Brussels - although he admitted the situation was 'incredibly complicated'.
The latest signs that a breakthrough is imminent came despite both Downing Street and Ireland trying to play down expectations. Irish deputy PM Simon Coveney said a deal should not be 'taken for granted', while Michel Barnier warned there was 'much more work to be done'.
Some ministers and civil servants had expected the PM to call a meeting of her senior team to sign off a deal today.
But it is understood there is now 'zero' chance of Cabinet gathering before the weekend.
The delay comes amid unrest over the details of a proposed compromise on the Irish border 'backstop' - the final stumbling block in the fraught talks with the EU.
The backstop is intended to avoid a hard border between Northern Ireland and the Republic, and would only come into effect if no wider trade agreement is sealed by the end of a mooted transition period in December 2020.
But Eurosceptics are anxious that it would effectively end up as the default position, leaving the UK permanently stuck in a customs union with the EU and unable to strike trade deals elsewhere.
Attorney General Geoffrey Cox, an eminent QC and Brexiteer who has emerged as a key player in the drama, boosted Mrs May at a Cabinet meeting earlier this week by suggesting a 'review' clause on the backstop could be an effective escape route.
But ministers including Michael Gove have demanded to be shown full legal advice before signing off the plan.
Senior figures including Brexit Secretary Dominic Raab had previously been pushing for the UK to be able to scrap the backstop unilaterally with a three-six month notice period - but the EU has said it will never agree to such a mechanism.
Transport Secretary Chris Grayling also voiced concerns about accepting EU rules on state aid, workers' rights and the environment, according to The Times. He suggested they could mean staying in the single market 'by the back door'.
Irish border backstop mechanism is the final hurdle in divorce talks
The Brexit divorce negotiations have boiled down to the issue of the Irish border.
Brussels had initially demanded that Northern Ireland stays within its jurisdiction for customs and most single market rules to avoid a hard border.
But Mrs May flatly rejected the idea, saying she would not agree to anything that risked splitting the UK. Instead, the government has mooted a temporary customs union for the whole UK, and accepted the need for extra regulatory checks in the Irish Sea.
Brussels has also given ground, and now appears to be prepared to sign off a UK-wide backstop in the divorce deal.
That leaves the mechanism for ending the backstop as the final hurdle to overcome - but the two sides have different views.
Dominic Raab has been arguing that the UK should be able to scrap the backstop arrangements by giving three to six months' notice.
That would assuage Eurosceptic fears that the country could end up being trapped in an inferior customs union indefinitely, unless the EU gives permission for it to stop or a wider trade deal is sealed.
For its part, the EU has been adamant that the backstop must offer an 'all-weather' solution to the Irish border issue and stay in place 'unless and until' it is superseded by other arrangements.
The bloc has already effectively killed off calls for a hard end date to the backstop - and No10 is now convinced that a simple unilateral notice period will not unlock the talks.
Mrs May and Irish PM Leo Varadkar have discussed a 'review mechanism' for the backstop, which could involve an independent arbitration body assessing whether the terms were being honoured and if the arrangement should be ended.
Potentially this could provide a solution that allows Mrs May to say the backstop would not go on for ever.
But the devil will be in the detail, and ministers are keen to ensure there are 'robust' ways for the UK to escape.
Both Labour and the DUP, whose party props up the Government, have gone further by demanding the legal advice is made public.
They received backing today from former Cabinet minister David Davis.
Shadow Brexit Secretary Keir Starmer has threatened to force the Government's hand in Parliament.
Downing Street is resisting the demands pointing out the constitutional principle is not to comment on private legal advice.
According to Austrian newspaper Der Standard, the EU commission is anticipating technical agreement between the negotiating teams on Monday. Once it is passed by the UK Cabinet, a Brussels summit of leaders will be triggered for November 25.
Commission President Jean-Claude Juncker told reporters in Helsinki today that Mrs May 'is, as we are, decided to have the deal, and we will have a deal'.
Asked if an agreement was coming soon, EU council chief Donald Tusk told Channel 4 News: 'I hope so ... but still we need maybe five, maybe six, maybe seven days.'
Tory Brexiteer Jacob Rees-Mogg heaped pressure on Mrs May as she faces a nail-biting vote in Parliament. He said the idea of a 'review' clause in the backstop was 'completely absurd'.
'Brexit means we can already leave the customs union when we want to, why should we give that up? It is a breach of faith with the electorate to stay in it under the authority of a third party,' he told The Sun.
'We are already seeing evidence that this arbitration mechanism is building our numbers. One colleague who is wavering about what to do has approached me in the last 24 hours to say he will vote with us if Mrs May goes ahead with this.'
Ministers were finally given access yesterday to the current text of the withdrawal agreement – minus the section on the Irish border.
Described as '95 per cent complete', the agreement covers the divorce bill, rights of EU nationals living in the UK and other issues.
Sir Jeffrey Donaldson, the DUP's chief whip, said publishing the advice would be in the public interest. 'It's because it affects the whole UK, therefore it shouldn't just be the DUP that sees this advice, or the Government,' he said.
'If the House of Commons is going to have a meaningful vote on a deal that includes, and upon which this legal advice is very, very important, then I think people are entitled to know what that advice is.'
Sir Keir, who spent yesterday in Brussels for discussions with EU officials, warned of the dangers of a so-called 'blind Brexit' where the details on future relations are unclear. He warned Labour was preparing to vote down any proposal if the accompanying document outlining the future relationship lacked detail.
On the legal advice, he said: 'That legal advice should be made available to Parliament when we come to vote on a deal. We need the position, we need to know precisely what advice has been given.
'I hope the Government has the good sense to realise that this is so important that it makes it available in Parliament for us to see.
'If they don't then obviously we'll have to think about what devices, what procedures, we can use to force them to do so.
'My invitation to the PM is, given the importance of the backstop, given the binding nature of the treaty that Parliament is going to have to look at, it is right that this advice is disclosed at the appropriate time so MPs can see it.' He added: 'The concern is that the future relationship with the EU will become a vague description, a vague document that is essentially a blind Brexit.
'We're here to deliver the message and to discuss the fact it is not acceptable to expect the Labour party or any parliamentarian to vote for a blind Brexit.'
Mrs May yesterday phoned European Council president Donald Tusk to push for an agreement. She spoke to German chancellor Angela Merkel on Tuesday evening.