Prime Minister Theresa May has suffered a fresh defeat in a Commons vote on her Brexit strategy by 303 to 258.
Labour leader Jeremy Corbyn has called on the prime minister – who was not in the Commons chamber for the vote – to "admit her Brexit strategy has failed".
Tory rebels abstained, saying the government's motion implied a no-deal Brexit would be ruled out.
Ministers said that was not the case but defeat would make life more difficult for the PM in EU talks.
Mrs May has promised MPs a final, decisive vote on her Brexit deal with the EU when she has secured the changes to it she believes MPs want to see.
A Labour amendment calling for that final, meaningful vote to be held before 27 February was earlier defeated by 16 votes.
An SNP amendment, which was also backed by the Liberal Democrats, calling for Britain's departure from the EU on 29 March to be delayed by three months, was defeated by 93 votes to 315, after most Labour MPs abstained.
Downing Street had earlier warned that a defeat in Thursday's vote could damage the prime minister's negotiating position, as she seeks to make changes to the controversial backstop "insurance policy" in the deal to avoid customs checks between Northern Ireland and the Republic of Ireland.
Mrs May believes she can secure a Commons majority for the deal if she can get legally-binding changes to the backstop clause – something the EU has consistently ruled out.
Labour has accused her of "running down the clock" so that MPs will be faced with a last-minute choice between her deal and no deal.
The defeat is Mrs May's tenth in a Commons vote since becoming PM.