Prime Minister Theresa May's Brexit deal has come under fire from allies and opponents alike after the government was forced to publish legal advice showing the United Kingdom could be locked indefinitely in the European Union's orbit.
After a string of humiliating parliamentary defeats for May on Tuesday cast new doubt over her ability to get a deal approved, US investment bank JP Morgan said the chances of Britain calling off Brexit altogether had increased.
As investors and allies tried to work out the ultimate destination for the world's fifth-largest economy, the Northern Irish party that props up May's government said legal advice about the deal was "devastating".
May was forced by parliament to publish advice from the government's top lawyer about the fallback mechanism, or backstop, to prevent the return of border controls between British-ruled Northern Ireland and the EU-member Irish Republic.
"Despite statements in the protocol that it is not intended to be permanent and the clear intention of the parties that it should be replaced by alternative, permanent arrangements, in international law the protocol would endure indefinitely until a superseding agreement took its place," the advice says.
"In the absence of a right of termination, there is a legal risk that the United Kingdom might become subject to protracted and repeating rounds of negotiations."
Brexit has repeatedly plunged British politics into crisis since the shock 2016 vote to leave the EU.
Now May is trying to get her deal approved by a parliament which shows every sign of striking it in a vote on December 11.
It is unclear what happens if the deal is rejected as Britain is due to leave on March 29.
Senior EU diplomats said they might be able to help May by making small changes to the deal she agreed with other EU leaders last month before she tries again to get support in parliament.
Nigel Dodds, deputy leader of the Northern Irish Democratic Unionist Party, confirmed the DUP intended to vote against May's plan next week but it would continue to support her government.
"Having achieved our aim, trying to get to a better deal, it would be a bit illogical to turn around the next day and say, right, let's get the government out," Dodds told ITV television.
A group of MPs who want a more definitive break from the EU than envisaged by May's plan said the government had invited senior MPs to a briefing on Thursday at its emergency planning body on the impact of a no-deal Brexit.
A source from within the group dismissed the move as an attempt to spook senior parliamentarians.
On Wednesday, one of May's chief party enforcers listened to the concerns of Eurosceptics in her governing Conservative Party and DUP.