But if Johnson loses, the UK will be hurled into an unprecedented political and constitutional crisis, with a potentially severe impact on trade, hitting supplies of food and fuel, and sparking civil disorder.
Johnson has vowed he will seek to force the UK out of the EU on Oct. 31 even if MPs reject his divorce accord Saturday -- without an agreement to soften the impact on the economy and society.
His opponents in Parliament are aiming to stop him by using a new law under which he is required to write to the EU by the end of the day Saturday seeking to secure an extension to the Brexit
deadline, if he hasn’t won MPs’ backing for his deal, or for a no-deal split.
Johnson says he will keep fighting to exit the EU on time, whatever the cost. The clash could end up with legal challenges against the government within days, potentially concluding in the UK Supreme Court.
An emergency 11th hour summit in Brussels, a general election, another attempt to pass a vote in Parliament, and even another referendum could all follow.
Without a majority in the Commons, and having alienated his Northern Irish allies, who prop up his government, Johnson faces a struggle to secure the votes he needs to prevail.
He spent Friday trying to woo skeptical MPs in his own party as well as opposition Labour politicians who represent pro-Brexit districts. The result looks set to be too close to call, and Johnson’s team believe they’re making progress, according to an official who asked not to be named.
“Imagine what it could be like tomorrow evening, if we have settled this, and we have respected the will of the people, because we will then have a chance to move on,” Johnson said in an interview with BBC TV on Friday. “This has been a long, exhausting and quite divisive business.”
Johnson received a boost from the EU when French President Emmanuel Macron said even if Parliament rejected the deal, there would be no further delay to Brexit day beyond the current deadline of Oct. 31.
That added to the pressure on MPs who would prefer another extension to the deadline to leaving the EU without a deal.
Opponents of Johnson’s threat to pursue a no-deal Brexit moved to reinforce their options.
Former Tory cabinet minister Oliver Letwin is proposing an amendment to the motion to approve Johnson’s exit accord that he says will act as an insurance policy to make sure the UK can’t an accidentally fall out of the EU with no-deal on Oct. 31.
Letwin’s amendment, which may be voted on before Johnson’s deal gets a chance to be put to MPs for approval, would withhold Parliament’s endorsement for the exit agreement until a new law is in place implementing Brexit.
A group of Labour MPs have put forward an amendment to Johnson’s motion that would give Parliament’s backing to a referendum on any deal agreed with the EU.
Johnson sought to woo Labour MPs with a promise to make commitments that ensure increased protection of workers’ rights and environmental standards in domestic law as the UK leaves the EU.
A separate new pledge from Downing Street would increase parliamentary scrutiny of the negotiations on the future partnership trade deal between the UK and the EU.