Britain and the EU have identified the "landing zones" to finally strike the Brexit trade deal, Ireland's prime minister said on Tuesday, as Boris Johnson warned Cabinet that talks could still fail.
The finalised zero tariff trade agreement could be announced as soon as Monday, Brussels sources said, but only if the UK made compromises.
The UK and EU both warned divisions remained over the key issues of fishing, the level playing field guarantees and the deal's enforcement and that the negotiations could still collapse.
Micheál Martin, the Irish Taoiseach, told the Bloomberg New Economy Forum that both sides could see "the landing zones" around the deal.
"Will the decision be made in London to go for it and say lets get a deal done? Some of us think that's an issue that has yet to be determined," he said before warning no deal would be "politically damaging" for Britain.
It was reported on Monday that David Frost, the UK's chief negotiator, had told the Prime Minister the deal could be agreed by Tuesday but that was played down today by Number 10.
Boris Johnson told the Cabinet in London that significant differences remained between the two sides after senior EU figures said this week was critical for the trade negotiations, which are ongoing in Brussels this week.
A Downing Street spokesman said, "The UK is keen to secure a deal with the EU, but not at the cost of our core principles around sovereignty and control over our laws, borders, money - and our fish.
"We are working hard to find solutions which fully respect UK sovereignty, but it is far from certain that an agreement will prove possible and time is now very short."
The National Federation of Fishermen's Organisations (NFFO) urged Mr Johnson not to sell out the UK fishing industry with an unpalatable compromise to get a deal with Brussels.
"No other country in the world gives away its fish in the way the UK has for the last 40 years. This is the time to right these wrongs," the NFFO and Scottish Fishermen's Federation wrote to the prime minister.
Mr Martin's comments came as it emerged Michel Barnier plans to brief EU ambassadors on Friday, amid mounting speculation a deal could be done.
It will be the first time in more than two weeks of intensified negotiations that the EU's chief negotiator formally updates envoys of the 27 remaining member states on the talks.
EU sources warned that any deal would still need the UK to compromise on the three major stumbling blocks.
The meeting of ambassadors in Brussels could be delayed until Sunday, if necessary, paving the way for Monday's announcement.
An EU official confirmed the plan but warned, "Of course, these things can move a million times between now and then."
EU figures believe a major breakthrough is needed in the next seven to ten days so that the European Parliament has time to ratify the finalised agreement before the end of the year no deal deadline.
On Monday, a senior EU diplomat predicted the EU would find a "creative solution" to ease the ratification logjam and prevent an accidental no deal exit on January 1, if a deal was struck too late to be approved in time.
A no deal would mean the UK and EU trading on less lucrative WTO terms.