DUP MPs have voted with Labour and other opposition parties to block the government's timetable to pass key Brexit legislation.
The government won a vote on its Brexit bill, but a second vote on a plan to implement the law was lost by 14 votes.
Number 10 had wanted MPs to allow the bill to pass through Parliament in the space of three days.
Boris Johnson said he will now "pause" the legislation and speak to EU leaders about a delay to the Brexit deadline.
The prime minister was forced to ask for an extension, but unless the EU grants one, the UK is due to leave the EU with no deal on 31 October.
European Council President Donald Tusk tweeted on Tuesday night that he would recommend the EU accept the UK's request for an extension.
Following PM @BorisJohnson’s decision to pause the process of ratification of the Withdrawal Agreement, and in order to avoid a no-deal #Brexit, I will recommend the EU27 accept the UK request for an extension. For this I will propose a written procedure.— Donald Tusk (@eucopresident) October 22, 2019
The DUP voted against both the government's Brexit deal and against the timetable for putting it through Parliament.
The party's chief whip, Sir Jeffrey Donaldson, said MPs needed "much more time" to scrutinise the bill, which the government wanted to push through Parliament in the course of this week.
DUP deputy leader Nigel Dodds said MPs had made a "very wise" decision to vote down the timetable, also known as a programme motion.
He said the vote would allow "further time for detailed examination of some of the most important legislation that we will ever have to consider, particularly given the impact on Northern Ireland".
Mr Dodds then addressed the PM directly and asked him to sit down with the DUP to discuss the detail in the Brexit bill.
"Talk to us again about what can be done at this late stage to ensure we join in this great quest together to get Brexit done, but as one United Kingdom," he said.
Independent Unionist Lady Hermon, MP for North Down, also voted against the timetable motion.
It means that all Northern Ireland MPs who take their seats in the chamber voted to oppose the government on two fronts on Tuesday night.
Sinn Féin has seven MPs but they abstain from taking their seats in the House of Commons.
Reacting to the results, Taoiseach (Irish Prime Minister) Leo Varadkar tweeted: "It's welcome that the House of Commons voted by a clear majority in favour of legislation needed to enact Withdrawal Agreement.
"We will now await further developments from London and Brussels about next steps including timetable for the legislation and the need for an extension."
The European Commission's chief spokeswoman said her organisation takes note" of the results of the Westminster vote and "expects the UK government to inform us about the next step".
She added that the President of the European Council Donald Tusk "is consulting leaders on the UK's request for an extension until 31 January 2020".