European Union leaders have already agreed one delay to Brexit, from March 29 to April 12, and Tusk has warned there is "little reason to believe" the British parliament can ratify May's deal by June 30.
European Union leaders agreed to grant British Prime Minister Theresa May a new Brexit deadline of October 31, diplomats told Reuters after French President Emmanuel Macron opposed summit efforts to give her another year.
The Prime Minister, however, remains under intense pressure from Conservative MPs - already angry at the failure to leave on March 29 as planned - who oppose any further delay.
Mr Macron is concerned that letting Britain stay too long would distract the EU from other issues - notably next month's European Parliament elections.
May pleaded with them at an emergency summit to delay Britain's exit, due on Saturday, until June 30 while the United Kingdom sorts out the mess that Brexit has become.
European leaders agreed with Britain on Thursday to delay Brexit by up to 6 months, saving the continent from what could have been a chaotic no-deal departure at the end of the week.
"One possibility would be a flexible extension, which would last only as long as necessary and no longer than one year, as beyond that date we will need to decide unanimously on some key European projects".
Most EU leaders have indicated they could accept such an extension as long as Britain pledges not use it to play an obstructionist course and undermine EU policies.
Leader of the Brexit Party and MEP Nigel Farage speaks to the press inside the EU Council headquarters in Brussels. In contrast to some testy recent summits, there were signs of warmth and even humor. But a drive by Macron to keep London on a tight leash saw the emergency summit bogged down in late-night wrangling as German Chancellor Angela Merkel and others argued the merits of a longer lag.
"The duration of an extension - it has got to be in line with the goal of any such extension", Barnier told a news conference on Tuesday.
And if the European Council did not agree on an extension at all, "there would be a risk of an accidental no-deal Brexit", he said. "But we will organise this extension such that when Britain has passed the Withdrawal Agreement, Britain can very quickly thereafter execute the exit in an orderly fashion", Merkel said.
Sir Bill, who represents Stone in Staffordshire, has made the legal action threat in a letter sent to European Council President Donald Tusk today. She has tried four times before and each time it has been rejected.
"If the withdrawal agreement is ratified by both parties before this date, the withdrawal will take place on the first day of the following month", the draft stated. Several days of talks between May's Conservative government and the main opposition Labour Party aimed at finding a compromise have failed to produce a breakthrough. It is Parliament that has forced this on the Government, ' he said.
The two sides said they would resume their discussions after Wednesday's European Union summit.