The British Prime Minister will plead with European Union leaders to give ground in order to help her Brexit deal survive next week's Commons showdown.
After talks earlier this week in Brussels broke down, Theresa May said the decisions made by the EU in the coming days would have a "big impact" on the fate of the deal.
MPs will vote on Tuesday on whether to back the Withdrawal Agreement as Mrs May seeks further concessions on the Northern Ireland backstop in order to reverse the humiliating 230-vote defeat suffered the last time the Commons passed judgment on her Brexit deal.
She will use a speech in Grimsby to say the government remains determined to secure legally binding changes to the backstop, and will urge the EU to agree.
"Just as MPs will face a big choice next week, the EU has to make a choice too," she will say.
"We are both participants in this process.
"It is in the European interest for the UK to leave with a deal.
"We are working with them but the decisions that the European Union makes over the next few days will have a big impact on the outcome of the vote."
Negotiators are preparing to work through the weekend in a frantic effort to break the deadlock over the backstop measures, which are aimed at preventing a hard border with Ireland if no alternative trading arrangements are in place.
EU officials are reported to have given the UK until tomorrow to come back with fresh proposals after "difficult" talks earlier this week failed to make a breakthrough.
The European Commission confirmed "technical talks" were continuing and said president Jean-Claude Juncker was "available 24/7" to meet Mrs May if a deal was close.
In the House of Commons, Attorney General Geoffrey Cox - who has been leading for the UK in the latest negotiations - said the talks would "almost certainly" carry on through the weekend.
In practical terms the Government needs an agreement by Sunday night at the latest as any new documentation relating to the deal must be published by Monday - the day before the vote.
Mr Cox and Brexit Secretary Stephen Barclay are thought likely to return to Brussels on Friday in a final bid to secure an agreement ahead of next week's crunch vote.
Number 10 is believed to hope a deal can be reached by Sunday night, with the possibility of the Prime Minister travelling to Brussels on Monday morning to meet Mr Juncker.
Ministers were said to be braced for another heavy defeat on Tuesday after the previous "meaningful vote" was lost by a majority of 230, with many MPs deeply unhappy about the backstop.
Mr Cox told MPs he was continuing to press for legally binding changes to the backstop, which would ensure the UK could not be tied indefinitely to EU rules.
He rejected claims that the government had again failed to come forward with concrete proposals, insisting there had been "focused, detailed and careful discussions".
"We are discussing text with the European Union," he said.
"I am surprised to hear the comments that have emerged over the last 48 hours the proposals are not clear. They are as clear as day and we are continuing to discuss them."
However there was clear frustration on the EU side, with chief negotiator Michel Barnier reportedly complaining that Mr Cox had produced "a legal solution to a political problem" and France's Europe minister Nathalie Loiseau saying they were still waiting for a "sustainable proposal" from the British side.