GRIMSBY, England (Reuters) – Prime Minister Theresa May urged the European Union on Friday to make “just one more push” to break the Brexit deadlock but proposals from the bloc’s chief negotiator fell short of anything that would win over the British parliament.

Three weeks before Britain is due to leave the EU, May has failed so far to get the changes to her divorce deal that she believes would gain the support of lawmakers, who handed the government a defeat of record proportions in January.

In a last-ditch appeal to the EU and to lawmakers at home, May said in a speech it was time to end the uncertainty over Brexit and for parliament to approve the deal on Tuesday.

Under pressure from some lawmakers in her own Conservative Party, May has sought legally binding assurances from the EU that Britain will not be trapped permanently in the so-called Northern Irish backstop, an insurance policy aimed at preventing the return of border controls between Northern Ireland and Ireland.

After she spoke, chief EU Brexit negotiator Michel Barnier announced he was ready to give Britain the unilateral right to leave the bloc’s customs union.

But he said London would need to honour its commitment to keep the Irish border free of controls, potentially leaving Northern Ireland subject to EU rules, with a “border” in the Irish Sea between Northern Ireland and the island of Britain.

That requirement has been rejected previously by London and would be particularly unpalatable to Northern Ireland’s Democratic Unionist Party, which props up May’s minority government in parliament and opposes any proposals for Northern Ireland to have different rules from the rest of the United Kingdom.

Stephen Barclay, Britain’s Brexit minister, said it was “not the time to rerun old arguments. The UK has put forward clear new proposals. We now need to agree a balanced solution that can work for both sides.”

Sky News cited sources in the DUP as saying Barnier’s proposal was a “non-starter”. A government source said that Britain was “not impressed” by the proposals.

‘SIGN OF DESPERATION’

In her speech in the northern English port of Grimsby, where 70 percent voted to leave the EU in the 2016 referendum, May said lawmakers risked putting Britain’s departure into doubt or triggering many more months of arguments over the country’s biggest shift in foreign and trade policy for decades.

The Brexit effort “needs just one more push to address the final, specific concerns of our parliament,” she said.

“So let’s not hold back. Let’s do what is necessary for MPs (members of parliament) to back the deal on Tuesday.”

Asked if she was responsible for the uncertainty that has forced many businesses to put off investment decisions, May again said there was only one way to ease their concerns – and that was to vote for her deal and move on.

Otherwise, she said Brexit might never happen and voters would be betrayed. Or, she added, Britain could leave without a deal to soften the shock, a nightmare scenario for many companies.

Those arguments largely restated her well-worn line. Eurosceptics say her agreement does not offer a clean break with the EU, while EU supporters want to maintain closer ties.

Jeremy Corbyn, leader of the main opposition Labour Party, said the appeal was “more like a sign of desperation”.

“These are very serious times. We don’t need any more delays and dithering by the government,” he told Sky News. “They’ve got to recognise her deal isn’t going to work, it doesn’t get support, and will not get through parliament.”

It was the first time that May had turned directly to the EU, showing signs of frustration that talks to secure changes to the backstop this week had as yet produced no breakthrough.

That frustration was matched on the EU side. Irish Prime Minister Leo Varadkar said the British, not the EU, had to compromise, and the decision to leave the bloc had been “a problem of their own creation”.

BLAME GAME?

EU diplomats, responding to excerpts of May’s speech released overnight, said she was preparing to blame the bloc for a fresh defeat of her plan.

“We are expecting a blame game after she loses the second ‘meaningful vote’ next week, so it looks like she is already preparing the ground for this,” one of the diplomats said.

If May’s plan is defeated on Tuesday, lawmakers will be able to vote on Wednesday and Thursday on whether they want to leave the bloc without a deal, or ask for a delay to Brexit beyond the scheduled date of March 29 – all but wresting control of Brexit from the government.

In a last-minute flurry of diplomatic activity, May was due to speak to EU leaders by telephone over the weekend and a European Commission spokesman said “intensive work” was going on between London and Brussels.

Attorney General Geoffrey Cox, charged with negotiating the changes to the deal, or another member of the government, could travel to Brussels on Saturday or Sunday if the talks progress.

Foreign minister Jeremy Hunt held out some hope that a deal was “entirely possible” in time for the vote.