LONDON, United Kingdom (AP) — Britain’s attorney general punctured Prime Minister Theresa May’s hopes of winning backing for her Brexit deal Tuesday, saying last-minute changes secured from the European Union didn’t give Britain the power to cut itself free of ties to the bloc.

Hard-core Brexit backers in Parliament came to the same conclusion, saying they wouldn’t support the deal in the House of Commons.

The assessments left May’s deal hanging by a thread. With EU leaders warning there would be no more changes or negotiations, and less than three weeks to go until the UK is due to leave, British lawmakers were facing a stark choice: support a deal many consider inadequate or run the risk that Brexit might happen chaotically, or not at all.

Parliament is due to vote later on the divorce deal, a day after talks with the EU produced promises that a contentious section of the agreement couldn’t be used to tie Britain to the bloc indefinitely.

Attorney General Geoffrey Cox said changes “reduce the risk” Britain could be trapped inside EU regulations — but do not eliminate it. The two-page opinion said the UK could still not extract itself from the terms of the divorce deal unilaterally, a key demand of pro-Brexit British politicians.

In a written legal opinion , Cox said that if UK-EU negotiations became stalled through “intractable differences,” Britain would have “no internationally lawful means of exiting the Protocol’s arrangements, save by agreement.”

“These improvements do make a difference,” Cox later told the House of Commons, telling lawmakers that whether to back the deal was “a political decision each of us must make.”

Lawmakers defeated May’s deal by a whopping 230 votes in January, but May hoped the changes she secured from the bloc would be enough to persuade many to change their minds.

That appeared unlikely after Cox’s assessment.

The European Research Group of pro-Brexit Conservatives, which has dozens of lawmakers as members, said the amendments “do not deliver ‘legally binding changes'” to the withdrawal agreement, as the government promised.

“In light of our own legal analysis and others, we do not recommend accepting the government’s motion today,” group member Bill Cash said.

John Whittingdale, a Brexit-supporting Conservative lawmaker, said the attorney general’s advice was “pretty terminal” for May’s plan. Another Brexiteer, Owen Paterson, tweeted that Cox’s opinion made it “brutally clear” that nothing had changed.

The main opposition Labour Party also maintained its opposition to the deal.

“The attorney general has confirmed that there have been no significant changes to the withdrawal agreement despite the legal documents that were agreed last night,” Labour Brexit spokesman Keir Starmer said. “The government’s strategy is now in tatters.”

The pound, which had risen on hopes the deal would be passed, slumped by more than one per cent against the dollar after Cox’s assessment, to trade at US$1.3108.

Other EU nations welcomed the overnight agreement, and urged British politicians to seize the chance to back the deal and ensure an orderly departure.

German EU affairs minister Michael Roth, called it “a far-reaching compromise.” Dutch Prime Minister Mark Rutte said in a Twitter message that he was “pleased with the agreement,” adding: “An orderly #Brexit is crucial for both the EU and the UK. There is no alternative.”

May flew to Strasbourg, France, late Monday for talks with European Commission President Jean-Claude Juncker. At a news conference following the meeting, they announced changes designed to overcome lawmakers’ concerns about provisions designed to ensure the border between EU member Ireland and Britain’s Northern Ireland remains open after Brexit.

The mechanism, known as the backstop, is a safeguard that would keep the UK in a customs union with the EU until a permanent new trading relationship is in place. Brexit supporters in Britain fear the backstop could be used to bind the country to EU regulations indefinitely.

May said documents to be added to the deal provided “legally binding” assurances that the backstop would be temporary and that Britain would have a way to get out of it if the EU failed to negotiate in good faith. The two sides also agreed to continue working on technology that would do away with the need for border checks. However, the text of the 585-page withdrawal agreement remains unchanged.

The EU warned British politicians that negotiations will not be reopened if Parliament rejects the deal again.

“In politics, sometimes you get a second chance. It is what you do with this second chance that counts. Because there will be no third chance,” Juncker said

“Let’s be crystal clear about the choice: it is this deal or Brexit might not happen at all,” he said.

Britain’s political impasse over Brexit has raised fears of a chaotic “no-deal” Brexit that could mean major disruption for businesses and people in the UK and the 27 remaining EU countries, with tariffs and border checks imposed on trade between the two.

If Parliament throws out May’s deal again on Tuesday, lawmakers will vote over the following two days on whether to leave the EU without an agreement — an idea likely to be rejected — or to ask the EU to delay Brexit beyond the scheduled March 29 departure date.

Even if the deal is approved, Brexit Secretary Stephen Barclay said there might need to be a “technical extension” so that all the needed laws can be passed.

Delaying Brexit would need the approval from all 27 remaining EU countries. They are likely to agree, as long as Britain leaves before elections to the European parliament in late May.

Some British lawmakers warned their Brexit-backing colleagues that rejecting the deal could lead to Britain’s departure being postponed indefinitely, because a delay would give momentum to opponents of Brexit.

“Today is our Hotel California moment. If we don’t check out tonight, we may never leave,” tweeted Conservative legislator Bob Seely.