Contrary to expectations in Westminster, the prime minister decided to send MPs home on Thursday, with the warning that they could be called back at any time in the next two weeks to rush through ratifying legislation.
A No 10 source said talks were expected to continue in Brussels “over the coming days” and the recall could be “as early as next week”.
Signals from Brussels suggested that the two sides are inching towards agreement, with little more than a fortnight to go before the 31 December deadline to avoid a no-deal Brexit.
The departure of MPs and peers will intensify pressure for a swift agreement by adding potential delays into the legislative process needed for any deal to become law by the end of 2020.
MPs had been bracing themselves to wait until at least Tuesday for their festive recess to begin, in case of agreement being reached during the coming days.
But Downing Street’s announcement, set to be approved in the Commons on Thursday, made clear that the chief negotiators, David Frost and Michel Barnier, need more time for talks in Brussels.
The European Commission president, Ursula von der Leyen, gave her most optimistic assessment yet of the chances of a deal, telling MEPs that there was now “a path to an agreement” after concessions from the UK on the thorny issue of common standards.
In what appeared to be a piece of theatrics designed to convince a domestic audience that Mr Johnson was not giving up ground, Downing Street insisted that no-deal remained the “most likely” outcome.
But Mr Johnson himself did not use this phrase in a press conference at No 10, instead saying there was “a good deal there to be done”.
The PM had earlier suggested that the onus was on the EU to make any concessions, telling the House of Commons that a deal depended on Brussels “seeing sense” over UK demands to control its own laws and fishing waters.
Downing Street has said that any deal reached before the end of 2020 will require legislative approval in both houses of parliament. Ms Von der Leyen has also promised a vote in the European parliament, which has agreed to meet as late as 28 December if necessary, though some in Brussels believe retrospective ratification is an option.
A No 10 spokesperson said: “Time is now in short supply to reach an agreement with the EU and we expect discussions will continue over the coming days.”
Parliament had continued to “do its duty” to deliver Brexit, with the last three bills required for departure from the EU set to receive royal assent by the end of Thursday, the spokesperson said.
“In the absence of further substantive business, we will – subject to the usual approval by the house – go into recess tomorrow, but with the knowledge that we will recall MPs and peers to legislate for a deal if one is secured,” he added. “That recall could be as early as next week.
“Parliament has long shown it can move at pace and the country would expect nothing less. The process for recall will align with the process for finalising the legislation for a deal, if one is secured, and no time will be lost.
“Under the recall process, we will adapt the days’ proceedings to focus exclusively on the passage of that legislation. This may mean meeting at an earlier time.”
Claire Fox, a former Brexit Party MEP put in the House of Lords by Mr Johnson, voiced alarm at the prospect of a last-minute deal being rushed through.
“How on earth can it be properly scrutinised?” she asked. “After four and a half years, you at least want to know what you are signing up to.”
Addressing the European parliament just 15 days before the UK leaves the single market and customs union, Ms Von der Leyen said she could still not say for sure whether talks that have stretched almost 11 months since the formal date of Brexit on 31 January would result in a free trade agreement.
“I cannot tell you whether there will be a deal or not, but I can tell you there is a path to an agreement now,” she said. “The path may be very narrow but it is there.
“The good news is that we have found a way forward on most issues, but this is now a case of us being so close and yet being so far away from each other because two issues still remain outstanding. You know them – a level playing field, and the fisheries."
But a UK official in Brussels said: “We’ve made some progress, but we are still very far apart in key areas.”
And leading backbench Conservative Brexiteer David Jones said Ms Von der Leyen’s claims of movement from the UK side may amount to no more than “spin”.
“I hope we get a deal, provided it satisfies the government’s position on sovereignty,” Mr Jones told The Independent. "Clearly it would be good but it remains to be seen what the proposals are.
“The EU has been putting out a lot of spin over the last few days. There’s no detail in what she has said. I would be very surprised indeed if David Frost moved his position.”
Ms Von der Leyen said that issues surrounding the governance of an eventual deal were now “largely being resolved”.
And she said a “big step forward” had been made on the decisive issue of common standards, with agreement on a “strong mechanism of non-regression”, which is understood to allow either side to challenge regulatory divergence by the other that could give it a competitive advantage.
But she said that issues still remain on “the question of how to really future-proof fair competition”, while on fisheries “the discussion is still very difficult”.
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