Prime Minister Theresa May says British MPs face a choice ahead of a vote on her Brexit deal: approving her deal or facing an exit with no deal or even the reversal of Brexit.
Ms May said she was speaking to MPs about giving parliament a bigger role in whether the Northern Irish backstop arrangement would be triggered, though she gave few details.
Ms May said some in parliament were trying to frustrate Brexit and that she did not think another referendum on Brexit was the right course.
"There are three options: one is to leave the European Union with a deal... the other two are that we leave without a deal or that we have no Brexit at all," Ms May told BBC radio on Thursday.
"It's clear that there are those in the House of Commons who want to frustrate Brexit... and overturn the vote of the British people and that's not right."
Ms May repeatedly sidestepped questions on whether she would delay the December 11 vote but did hint at possible concessions on the Northern Irish backstop.
"There are questions about how decisions are taken as to whether we go into the backstop, because that isn't an automatic," she said. "The question is: do we go into the backstop? Do we extend what I call the implementation period?"
When asked repeatedly what her plan B would be if her deal was rejected, she did not directly answer the questions.
Ms May's comments came as the Democratic Unionist Party (DUP) insisted it will withdraw support for her government if she presses ahead with the Brexit deal with the EU.
Asked if the DUP was prepared to precipitate a general election, the party's Brexit spokesman Sammy Wilson told BBC Radio: "If it comes to the point where the government makes, shows, a determination to implement the Withdrawal Agreement with its damaging terms at present, or some future version of it, which is still equally damaging, we will not be supporting the government."
Court ruling next week
The EU's top court will say on Monday whether Britain can unilaterally halt Brexit, potentially offering a boost to those opposed to leaving the European Union on the eve of a crucial and tumultuous vote in the British parliament.
In a brief statement on Thursday, the Court of Justice in Luxembourg said the justices would deliver a ruling on December 10 in a case brought by Scottish politicians who argue Britain can simply withdraw its plan to leave in March, without waiting for the approval of the other member states.
Ms May insists there is no question of her stopping Brexit.
But in a vote scheduled for next Tuesday, the treaty faces heavy opposition from MPs both for and against Britain leaving the bloc.
Acting with almost unprecedented speed in a case that the court took up only in October, and on which it held a hearing only last week, a legal adviser to the court said on Tuesday that Britain could indeed make a U-turn entirely of its own accord. Such advice is usually but not always followed by the judges.
The legal clarification of Article 50 of the EU treaty, under which Ms May last year triggered a two-year countdown to departure, matters because opponents of Brexit want to hold a second referendum that would give Britons a choice of staying in the EU. According to an advocate general at the ECJ, that choice is entirely theirs to make and does not need EU approval.
That makes the prospect of a new referendum credible, according to supporters of a 'people's vote'. The British electorate voted in 2016 to leave the EU by 52 percent to 48.
EU leaders have long insisted they would welcome Britain changing its mind, but many EU officials and legal experts had assumed that the approval of either all or most of the other 27 members states would be needed to halt Brexit altogether.