EU Council president Donald Tusk warned “the deep divisions within the House of Commons” meant European leaders had no faith the Prime Minister could reach a Brexit compromise with Labour and get it through Parliament by the end of June.
Instead, the EU is set to demand the UK “refrain” from any actions that “jeopardise the attainment of the Union’s objectives” while it remains a member of the bloc for up to a year more.
Under draft proposals to be considered Wednesday night, a flexible extension of between nine and 12 months could be reviewed in October, or ended on the first of the following month if the UK does manage to ratify the Brexit withdrawal agreement at any point.
The Prime Minister spent Tuesday holding talks with French president Emmanuel Macron in Paris and German chancellor Angela Merkel in Berlin, but has not managed to convince EU leaders that her plan to extend Article 50 until 30 June will deliver a smooth Brexit.
In an introductory letter to EU leaders ahead of tonight’s summit, Mr Tusk said that “whatever course of action is taken, it must not be influenced by negative emotions”.
The EU Council president published his letter with a tweet stating “there are times when you need to give time time”.
He wrote: “We should treat the UK with the highest respect, as we want to remain friends and close partners, and as we will still need to agree on our future relations. Neither side should be allowed to feel humiliated at any stage in this difficult process.”
But he cast doubt on the UK government’s ability to secure its own deal or agree a compromise in talks with Labour by its new preferred end date of 30 June.
“Given the risks posed by a no-deal Brexit for people and businesses on both sides of the English Channel, I trust that we will continue to do our utmost to avoid this scenario,” he wrote.
“However, our experience so far, as well as the deep divisions within the House of Commons, give us little reason to believe that the ratification process can be completed by the end of June.
“In reality, granting such an extension would increase the risk of a rolling series of short extensions and emergency summits, creating new cliff-edge dates.
“This, in turn, would almost certainly overshadow the business of the EU27 in the months ahead.
“The continued uncertainty would also be bad for our businesses and citizens.”
Mr Macron has warned an extension is not guaranteed, with his Europe minister Amelie de Montchalin saying Paris would insist on conditions limiting British influence on EU decision-making during the extension period.
The unanimous agreement of all 27 remaining EU states is needed to avoid a no-deal Brexit on the scheduled date of 12 April.
Ms de Montchalin warned “the position of France has not changed” and the EU27’s approval of Mrs May’s request was “neither settled nor automatic”.
“We want to understand what the UK needs this extension for,” she said.
“Then comes the question of the conditions – what role the UK wants to play during this extension, on what type of decisions it wants to play a role.”
Germany’s deputy foreign minister Michael Roth said that, despite the opening of cross-party talks, “so far absolutely nothing has changed” and “we are in a very, very frustrating situation here”.
“Within the European Union, there isn’t an endless readiness to keep talking about delays so long as there is no substantial progress on the British side,” Mr Roth warned.
In a bid to ease fears about a disruptive UK remaining in the EU until 2020, Mr Tusk said any delay would not be used to re-open the withdrawal agreement, and negotiations on the future relationship would be limited to the Political Declaration ‘blueprint’.
“The UK would have to maintain its sincere co-operation also during this crucial period,” Mr Tusk wrote.
The SNP’s Westminster leader Ian Blackford said the Prime Minister had to agree a Brexit delay long enough to hold a second EU referendum, with the option to remain in the bloc.
“The UK faces the Brexit cliff edge in just three days’ time,” Mr Blackford said.
“Theresa May must stop ignoring the wishes of the people of Scotland and put the brakes on Brexit.”
As talks with Labour on a possible compromise continued in London, there were signs of resistance in Mrs May’s Cabinet.
International trade secretary Liam Fox warned that a customs union would leave the UK “stuck in the worst of both worlds”.
In a letter to the chairman of the Tory backbench 1922 Committee, Dr Fox said: “In such a scenario the UK would have a new role in the global trading system – we ourselves would be traded.
“As the famous saying in Brussels goes, if you are not at the table, you are on the menu.”