U.K. Prime Minister Theresa May staggered into the final days of debate before a key parliamentary vote on her much-derided Brexit deal next week that could either cement the nation's exit from the European Union or trigger unprecedented chaos in British politics. 

May will attempt to win over both her rival opposition lawmakers in the Labour Party, as well as skeptical Conservative Party allies, in four days of parliamentary debate that begins Thursday and will culminate with a Commons vote on December 11 to support her deal to leave the European Union at the end of March.

However, should lawmakers decided to vote against it, as all indications suggest they will, a series of unpredictable options will be laid before the House, including the prospect of either fresh national elections or a second referendum on Britain's EU membership. 

"Within the 'no-Brexit' scenarios, a unilateral revocation on the U.K.'s part looks more likely to us than a joint U.K.-EU decision to extend the Article 50 negotiation period and thereby keep the existing clock running," wrote JPMorgan analysts Wednesday, which reduced its 2019 Brexit odds to 60-40. "And a second referendum strikes us as rather more likely than a general election to be driving a decision to revoke.  

May's exit plan, which she agreed with EU officials following more than a year of torturous negotiations, aims to maintain broad trade ties on goods with the bloc, but allows for just enough freedom for the UK to strike new arrangements with countries such as the U.S. and China. 

Or so May argues. 

"I don't say that this deal is perfect. It was never going to be. That's the nature of a negotiation," May told lawmakers Tuesday. "We should not let the search for the perfect Brexit prevent a good Brexit that delivers for the British people."

Others have said that, owing to the mechanics of relationship between EU member Ireland and the U.K. British territory of Northern Ireland, her deal binds the U.K. into an arrangement that means it will have to follow EU rules without having a say in how they're made.

Opposition leader Jeremy Corbyn, who is attempting to use the Brexit chaos to force an early election, went a step further, calling May's deal a "Blind Brexit", arguing it gives too much power to the government to negotiate a future trade deal based on a vague framework of objectives agree with Brussels. 

"We still don't know what our long term relationship with Europe would look like and that's way so many (lawmakers) are not willing to vote for this blindfold brexit and take a leap in the dark about Britain's future," he countered. 

That view was given support today by the publication -- against the Prime Minister's wishes -- of the full legal advice given to the government by Attorney General Geoffrey Cox when it reached its exit deal last month.

Cox warned that Britain could be locked into an EU customs union, preventing it from cutting trade deals elsewhere, and risks becoming subject to "protracted and repeating rounds" of negotiations with Brussels going forward.

Nigel Dodds, a member of the Democratic Unionist Party that props up May's government in a so-called "confidence arrangement", called the advice "devastating", cementing his vow to vote against the deal next week.

Much ground will be ploughed before that, however, as May attempts to weather the storm of three humiliating defeats in parliament yesterday, which censured her party for failing to publish the legal advice and handed more power to lawmakers to define future Brexit talks if her deal is voted down. 

But with the EU's top court declaring that Britain can unilaterally stop its Brexit process, the Bank of England warning that a "no-deal" Brexit would tip the economy into recession and lawmakers within her own party calling her deal a "betrayal" of the nation, her chances of winning more support, let alone a victory, look exceedingly unlikely.