May will spend Friday and the weekend trying to persuade opponents to support the withdrawal agreement, which Parliament has resoundingly defeated twice. That left Britain facing a disruptive "no-deal" exit on March 29, when a two-year countdown to departure runs out.
After months of deadlock over Brexit, the House of Commons voted Thursday to ask the EU to delay Britain's exit.
May hopes to win approval for her deal next week, then seek a delay until June 30. If it is rejected she says Britain will need a longer extension, which could see Brexit postponed indefinitely.