LONDON - Prime Minister Boris Johnson's plan to get Parliament to approve his divorce deal with the European Union was thrown into doubt Saturday, as lawmakers were first given a vote on whether - yet again - to delay their final decision on Brexit.
At a rare weekend sitting of Parliament, Johnson implored legislators to ratify the deal he struck this week with the other 27 EU leaders. He said members of the House of Commons should "come together as democrats to end this debilitating feud" over Brexit that has wracked the country since its June 2016 vote to leave the EU.
"Now is the time for this great House of Commons to come together... as I believe people at home are hoping and expecting," Johnson told lawmakers.
But he may not get the vote he craves. As the session of Parliament opened, House of Commons Speaker John Bercow said he would first allow a vote on an amendment that essentially puts the vote on the deal off until another day. Those behind the amendment say it will remove the risk that the U.K. could stumble out of the bloc without a deal on the Oct. 31 deadline - a prospect economists say would disrupt trade and plunge the economy into recession.
The amendment makes support for the deal conditional on the legislation to implement it being passed by Parliament, something that could take several days, or several weeks.
One of the lawmakers behind the measure, Oliver Letwin, said it would prevent the U.K. from leaving at the end of the month "by mistake if something goes wrong during the passage of the implementing legislation."
It would also give lawmakers another chance to scrutinize - and possibly change- the departure terms while the legislation is passing through Parliament.
Brexit Breakthrough, but British MPs Could Torpedo EU Deal video player.
If the amendment passes, Johnson will have to ask the EU for a delay to Britain's departure date. Last month Parliament passed a law compelling the government to do that if no deal is approved by Saturday.
The prime minister signaled that he would do that under duress. He is compelled by law to ask for the extension, but he said "it cannot change my judgment that further delay is pointless, expensive and deeply corrosive of public trust."
And he warned that the bloc's approval could not be guaranteed.
"There is very little appetite among our friends in the EU for this business to be protracted by one extra day," Johnson said. "They have had three and a half years of this debate."
As lawmakers gathered inside Parliament - their first Saturday sitting since the 1982 Falklands War - tens of thousands of anti-Brexit demonstrators were expected to march on the building, calling for a new referendum on whether to leave the EU or remain.
Since striking a deal with the EU on Thursday, Johnson has been imploring and arm-twisting both Conservative and opposition lawmakers as he tries to win majority support for his deal.
Johnson's Conservative Party holds only 288 seats in the 650-seat House of Commons, so he will have to rely on support from other parties and independent lawmakers to get over the line.
The result looks set to be close, although Johnson has had some success winning over both hard-core Conservative Brexiteers and a handful of opposition Labour lawmakers who represent pro-Brexit parts of the country.
Johnson hopes for success in getting a fractious Parliament to back the deal after his predecessor, Theresa May, failed three times to get lawmakers behind her plan.
His hopes of getting the deal through Parliament were dealt a blow when his Northern Ireland ally, the Democratic Unionist Party, said it would not back him. The party says Johnson's Brexit package - which carves out special status for Northern Ireland to keep an open border with EU member Ireland - is bad for the region and its bonds with the rest of the U.K.
"We will not be supporting the government, we will be voting against," said the party's deputy leader, Nigel Dodds. "Because it isn't Brexit for the whole of the United Kingdom."
To make up for the votes of 10 DUP lawmakers, Johnson has tried to persuade members of the left-of-center Labour Party to support the deal. Late Friday the government promised to bolster protections for the environment and workers' rights, to allay Labour fears that the Conservative government plans to slash those protections after Brexit.
Labour leader Jeremy Corbyn dismissed that promise as inadequate.
"This deal is not good for jobs, damaging for industry and a threat to our environment and natural world," he said.
"Supporting the government this afternoon would merely fire the starting pistol in a race to the bottom in regulations and standards."