British and European Union negotiators made a last-ditch effort on Monday to bridge stubborn differences standing in the way of a post-Brexit trade deal, but they had at best 48 hours left to avoid a disorderly parting of ways at the end of this month.

“EU-UK negotiations have entered the endgame, time is running out fast,” said EU diplomat after the bloc’s chief negotiator Michel Barnier gave member states’ envoys to Brussels a downbeat assessment of the state of play. “It is for the UK to chose between ... a positive outcome or a no deal outcome.”

With growing fears of “no-deal” chaos after London finally leaves the EU’s orbit on Dec. 31, talks resumed before British Prime Minister Boris Johnson and European Commission President Ursula von der Leyen review the situation in a call at 1600 GMT.

Irish Prime Minister Micheal Martin, whose country would be the hardest hit of the 27 EU states if there is no trade accord, put the chances of a deal at 50-50. Investment bank JPMorgan said its odds on a no-deal had risen to one third from 20%.

The British pound tumbled on concerns that there would be no agreement covering annual trade worth nearly $1 trillion.

Barnier told members of the European Parliament in a separate briefing that negotiations could go on until Wednesday, but no further, Ireland’s RTE news said. EU diplomats said the ball was now in Johnson’s court.

“People need to understand that the British are playing with fire here and the fire can burn everybody and that’s something we should all try to avoid,” said Mairead McGuinness, Ireland’s commissioner in the EU executive.

However, the Sun newspaper reported that Johnson, a figurehead for Britain’s campaign that led to a ‘vote leave’ victory in a 2016 referendum, was ready to pull out of the talks within hours unless Brussels changed its demands.

In London, a lawmaker in Johnson’s governing Conservative Party said France would have to make concessions on fishing, and the EU would have to drop what he said were new demands on fair competition known as the level playing field.

Britain, which joined the EU in 1973, formally left the bloc on Jan. 31 but has been in a transition period since then under which rules on trade, travel and business remain unchanged.

For weeks, the two sides have been haggling - as yet without a result - over fishing rights in British waters, ensuring fair competition for companies and ways to solve future disputes.

Failure to secure a deal would clog borders, upset financial markets and disrupt delicate supply chains across Europe and beyond as the world tries to cope with the vast economic cost of the COVID-19 pandemic.

Sterling fell by more than 1% to six-week lows versus the euro and also dropped against the dollar to $1.327, a U-turn in market sentiment from Friday when it had risen above $1.35 for the first time this year.

With just days left for a deal to be agreed, EU diplomats said it was a decisive moment for both the United Kingdom and the bloc which built the ruined nations of Europe into a global power after the devastation of World War Two.

In a move that could further undermine the talks, the British government will press ahead with draft laws this week that would breach London’s earlier divorce treaty with the bloc.

Junior Foreign Office Minister James Cleverly said on Monday the clauses that breach the treaty would be re-inserted.

Meanwhile,  British retail group Frasers is in talks to buy the UK activities of failed department store chain Debenhams, it announced on Monday.

Debenhams and Topshop owner Arcadia, two of Britain’s biggest clothing retailers, are on the brink of collapse owing to coronavirus fallout and fierce online competition, endangering 25,000 jobs.

Frasers is headed by Mike Ashley, owner of English Premier League football club Newcastle United and renowned for purchasing major retailers that have fallen from great heights.

In a statement, Frasers said that while it hoped to reach a deal with administrators of Debenhams, the outlook was complicated by the demise of Arcadia, which is the biggest concessions operator in its stores.

“The company confirms that it is in negotiations with the administrators of Debenhams’ UK business regarding a potential rescue transaction for Debenhams’ UK operations,” Frasers said in a brief statement.

“Whilst Frasers Group hopes that a rescue package can be put in place and jobs saved, time is short and the position is further complicated by the recent administration of the Arcadia Group.”

Administration is a process whereby a seriously troubled company drafts in outside expertise to try and salvage at least parts of the business.

In recent times, Ashley has rescued British department store chain House of Fraser.

The Frasers group also includes Ashley’s Sports Direct chain of shops as well as high-end clothing retailer Flannels and video-game outlets Game.

Debenhams, which has already been shedding thousands of jobs ahead of and during the pandemic, currently employs around 12,000 staff -- mostly being paid by the government under its Covid furlough scheme.