Theresa May held 11th-hour crisis talks with EU leaders on Sunday as she agonised over whether to postpone Tuesday's “doomed” vote on her Brexit deal.

With time rapidly running out, Mrs May phoned Donald Tusk, the European Council president, to explain that MPs would kill off the deal – and possibly her premiership – unless Brussels could throw her a lifeline.

Mrs May also called Leo Varadkar, the Irish Taoiseach, to discuss the vote and Thursday’s summit in Brussels. Mr Varadkar’s support is crucial if Mrs May is to win any concessions on the Irish backstop – the biggest obstacle to getting her deal through Parliament.

Even her closest allies were still unsure on Sunday whether she would postpone the vote in the hope of winning fresh concessions from EU leaders at a summit in Brussels on Thursday, or press ahead and use her expected defeat to prove to the EU that the deal is dead.

Mrs May has told aides the solution to her dilemma lies with Brussels, having all but accepted that the vote is unwinnable. But one senior minister said Mrs May did not have a clear plan, likening her strategy to Wilkins Micawber, the Dickens character who forever insists that “something will turn up”.