Theresa May will urge the EU to help get her Brexit deal through the Commons by agreeing legally binding changes to the controversial backstop.
On Friday, she’ll say the EU’s actions will “have a big impact on the outcome” when MPs vote on it next week.
But Labour’s Sir Keir Starmer said it was now “clear” the PM “will not be able to deliver the changes she promised to her failed Brexit deal”.
The EU says the UK must come forward with new ideas to break the deadlock.
The UK is due to leave on 29 March.
Mrs May will visit workers in Grimsby, Lincolnshire on Friday, days before the second “meaningful vote” in the House of Commons on the withdrawal deal she has negotiated with the EU.
She will tell them: “Just as MPs will face a big choice next week, the EU has to make a choice too.
“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.”
BBC political correspondent Ben Wright said making a public appeal to the EU for compromise just four days before the vote was an admission of how tough negotiations with the EU were proving.
What is the sticking point?
The first vote, in January, saw the deal rejected by 432 votes to 202, the largest defeat for a sitting government in history.
Mrs May is seeking legally-enforceable changes to the “backstop” – a controversial insurance policy designed to prevent physical checks on the border between Northern Ireland and the Republic of Ireland – but there have been few visible signs of progress.
Leading Brexiteers are looking for reassurances that the backstop – which would see the UK aligned with EU customs rules until the two sides’ future relationship is agreed or alternative arrangements worked out – will not endure indefinitely.
The European Commission said on Wednesday that “no solution has been identified” to the Irish backstop and it has refused to rewrite the withdrawal deal already struck, which is designed to ensure an orderly Brexit on 29 March and pave the way for trade talks.
But UK attorney general Geoffrey Cox said UK plans to solve the issue were “as clear as day” and talks with the EU would “almost certainly” continue throughout the weekend.
What does Labour say?
The Labour leadership wants the UK to remain in a customs union with the EU and Jeremy Corbyn met some Conservative MPs on Wednesday to discuss alternatives to the prime minister’s deal, if it is again rejected by Parliament.
Shadow Brexit secretary Sir Keir Starmer said: “It’s becoming increasingly clear that Theresa May will not be able to deliver the changes she promised to her failed Brexit deal. This speech looks set to be an admission of failure.
“After two years of negotiation, the government is simply incapable of delivering a Brexit deal that protects jobs, the economy and people’s livelihoods.”