MPs were again told that the options on the table include a legally binding time limit to the existing backstop or a unilateral exit clause - both of which have been roundly rejected by the EU.
"How it's achieved is not something to be purist about".
She said she was prepared to speed up other parts of the ratification process of the Brexit deal if time gets too tight to pass legislation before exit day - a move some interpreted as a sign she was willing to keep negotiating until the last moment. It's not possible to predict the future.
Will May delay Brexit vote to last minute?
Sir Keir, unlike his party leader Jeremy Corbyn, is an European Union enthusiast so there is some logic to his stances, which is to seek the softest possible Brexit.
Meanwhile, the group led by Ms Cooper and Sir Oliver said they were preparing plans to enable Parliament to prevent the country falling into a no-deal Brexit "by accident".
MPs last month overwhelmingly rejected the deal struck between May and Brussels and the British premier has since been attempting to secure changes that would satisfy parliament's lower House of Commons.
Switzerland is not a member of the European Union, but its relations with Britain are based on a long line of bilateral agreements between Bern and the bloc.
Meanwhile, Gavin Williamson, the UK's defense secretary, was set to put a positive spin on Brexit on Monday by saying it will offer the United Kingdom an opportunity to boost its global military standing and allow it to take a larger role in addressing threats.
Downing Street said Mrs May will make a Commons statement on the latest developments in the Brexit negotiations on Tuesday afternoon to give MPs more time to "digest the content" ahead of a series of expected Commons votes on Thursday.
Barnier said it was up to London to provide clarity on what is next - a view shared by Bettel.
Trump slams ‘vicious’ Democrats for conduct at testy Whitaker hearing
According to CNN , former Trump associate Roger Stone was "one of the last key campaign associates" to be investigated. Whitaker said he had not spoken with President Donald Trump about the matter in his tenure as acting Attorney General.
"We now all need to hold our nerve to get the changes this house has required and deliver Brexit on time", May is due to tell MPs.
It is by no means certain that Brussels will accede to the demands Mrs May is presenting on behalf of the British parliament - not least because it is unclear what those demands precisely are.
Anna Soubry has been one of the MPs arguing against Brexit.
As we talked about late on Monday, there has been a sense building in Westminster that the prime minister is, maybe by accident, maybe increasingly by design, looking to nearly the last possible minute for the definitive Brexit vote.
Brexit Secretary Stephen Barclay travelled to Brussels for talks with the EU's Chief Negotiator Michel Barnier on Monday evening to try to find a way out of the impasse.
Their teams would continue to work in the meantime "on finding a way forward", it added.
Negotiations of a kind have also been taking place back in Westminster, with an exchange of letters between Mrs May and Labour leader Jeremy Corbyn.
Replying to a letter from Labour leader Jeremy Corbyn, May agreed to more talks to break the political stalemate but stopped short of backing his call for a full customs union.
British government asked lawmakers on Sunday to give Prime Minister Theresa May more time.
The Prime Minister was heckled as she denied running down the clock, telling Mr Corbyn that she had "wanted to have this sorted before Christmas". If Britain leaves the European Union without a trade deal, that would mean a 10 percent import duty on cars and auto parts. If... this is not the case can the prime minister tell the house today when the meaningful vote will be?