UK Prime Minister Boris Johnson said he was going "to pause" efforts to get his Brexit deal with the EU into UK law after members of parliament rejected his plan to rush it through in three days.
After the result of the vote - 322 MPs to 308 - was announced, Johnson said it was now up to the European Union to decide whether to accept the official UK request for Brexit to be delayed from 31 October.
But he said that until their decision was known the UK would be stepping up preparations for leaving the EU without a deal in just over a week.
Despite the defeat on the timetabling of the legislation, Johnson had earlier won MPs' backing in principle for the bill by a bigger than expected 329 votes to 299. His predecessor Theresa May failed in three attempts to get MPs to back the deal she negotiated with the EU.
At the start of the debate ahead of the vote Johnson had said he would drop the bill and push for a general election if members of parliament rejected his timetable, saying: "I will in no way allow months more of this."
No party has a majority in the House of Commons at the moment, so the idea of an election is seen by many as a way to break the current deadlock on how, or whether, Brexit happens. Brexit would be likely to be the defining issue of the campaign.
The UK voted by 51.9 percent to 48.1 percent to leave the European Union in a referendum in 2016, but so far MPs have failed to agree on how Brexit happens and what the UK's future relations with the EU will be.
Jeremy Corbyn, leader of the main UK opposition party, said his recommendation was for his Labour MPs to vote against the deal and the proposed timetable.
Johnson became UK prime minister in July with a pledge to deliver Brexit on 31 October whether or not there was a deal with the EU. However MPs opposed to a no-deal Brexit passed a law which means the UK had to ask for a delay if a deal had not been passed by last Saturday.
That letter requesting an extension was sent on Saturday evening, and the EU has said it is considering the request.
So, although Johnson said he would "rather be dead in a ditch" than ask for a further delay to Brexit, it seems that a defeat in the vote on Tuesday evening will push back the proposed date of Brexit to 31 January, 2020, and prompt a general election campaign, with the vote itself thought most likely to be held on a Thursday in early December.