Prime Minister Boris Johnson warned parliament on Tuesday that if it delayed his Brexit legislation he would abandon his attempt to ratify the deal to leave the European Union and push for an election instead.
As the clock ticks down to the latest October 31 deadline for Britain's departure, Brexit is hanging in the balance as a divided parliament debates when, how and even whether it should happen.
After he was forced by opponents into the humiliation of asking the EU for a delay that he had vowed he would never seek, Johnson is battling to ram legislation through the House of Commons that will enact his last-minute Brexit deal.
In yet another day of high drama, lawmakers vote at around 1800 GMT on the second of three readings of the 115-page Withdrawal Agreement Bill - a procedural step that opens the stage when the law can be amended.
They will then vote on the government's extremely tight timetable for carrying it through the rest of the stages to become law, with opponents saying the government has not left enough time to consider it properly.
Johnson cautioned parliament that if it delayed Brexit again by defeating his timetable then he would pull the legislation and push for an election which he would fight under the slogan of "Get Brexit Done".
"The bill will have to be pulled," Johnson said when asked what he would do if parliament defeated him. "We will have to go forward to a general election."
Johnson needs parliament's support to trigger an early election because one is not scheduled until 2022. A source in the opposition Labour Party said it will back an election only if a delay to Brexit is agreed first, to ensure that Britain does not leave the EU without a deal before the vote.
Defeat in either of Tuesday's votes in parliament would appear to scupper Johnson's plans to leave the EU with an agreement on October 31. If the EU offers a delay, he is obliged to by law to accept it, although government ministers have still not ruled out somehow leaving with no deal on that date.
Even if Johnson wins both votes on Tuesday, his opponents in parliament could have another chance to ambush the government with amendments that could wreck his plans by demanding a much closer post-Brexit relationship with the EU.
Johnson said the best way to avoid a no-deal Brexit would be to approve his Brexit legislation, adding that the country was tired of the discussion in parliament.
Opposition leader Jeremy Corbyn said his Labour Party would oppose both the Bill itself and the accelerated timetable for enacting it. A small Northern Irish party that had propped up Johnson's government has said it will oppose the Bill.
Tuesday's votes could be very close and may depend on whether Johnson can win over enough pro-Brexit Labour rebels to offset opposition from Conservative lawmakers pushed out of his parliamentary party for defying him on earlier Brexit votes.
BREXIT IN PLAY
More than three years since the United Kingdom voted 52 percent to 48 percent to leave the European Union, the Brexit crisis is straining Britain's political and constitution system to the breaking point.
Johnson confounded his opponents by agreeing a Brexit deal with the EU on Thursday. But parliament did not pass a motion on Saturday expressing support for the deal, which meant Johnson was required to write to the EU asking for a delay.
He complied - reluctantly sending an unsigned photocopy of a letter asking for more time - but says he still wants to avoid the delay by getting his agreement enacted as law by October 31.
If Johnson is defeated on Tuesday, much will depend on how the EU plays yet another Brexit quandary.
European Council President Donald Tusk said he was discussing the request for a Brexit delay with the leaders of the other 27 member states and would make a decision "in the coming days".
"I have no doubt that we should treat the British request for an extension in all seriousness," Tusk told lawmakers in the Strasbourg assembly of the European Union parliament. "A no-deal Brexit will never be our decision", he said to applause from lawmakers.
In a sign of the frustration in Brussels, European Commission President Jean-Claude Juncker said Brexit was a waste of time and energy and that the European Parliament could only approve Johnson's deal after the British parliament.
Anti-EU campaigner Nigel Farage, whose Brexit Party won the most British seats at European elections this year, told the EU parliament that another delay was on the cards.
Behind the daily Brexit combat in parliament, in the courts and at late-night EU summits, a much bigger game is being played over whether Brexit will happen at all.
Johnson faces legislative booby traps at every juncture, but the opponents of Brexit are also deeply divided - one of the reasons their campaign to "Remain" failed in the 2016 vote.
Still, Johnson is asking a divided parliament where he has no majority to approve in just three days one of the most important pieces of legislation in recent British history.
If his accelerated timetable were adopted, the so-called WAB (Withdrawal Agreement Bill) would have less time for debate in the House of Commons than a law to ban the use of wild animals in circuses, according to the Institute for Government.
Previous bills to implement major European treaties have taken 10 to 40 days to get through parliament. Government ministers said parliament has enough time to discuss every intricacy of Brexit.