Tory MPs have snubbed a vote on halting plans to slash Universal Credit by £20 per week for millions of families.
Labour forced a symbolic Commons vote over the planned cut to the temporary uplift in April, in a bid to pile pressure on Chancellor Rishi Sunak to change course.
While the vote is not binding and families relying on the £20-a-week rise remain in limbo, the move forced Tory MPs to set their names to the Government's plan.
However Boris Johnson ordered Tories to sit on their hands after Conservative MPs faced a barrage of criticism for opposing a similar motion on free school meals last year.
The Commons supported the move by 278 votes to 0 - meaning a significant number of MPs abstained.
A small group of Tory rebels were expected to join Labour in backing the £20-a-week hike.
The £1,040-a-year uplift was brought in during the pandemic to help 6million families reliant on the benefit at a cost of £6bn to the Treasury.
It was due to end in April, but Mr Sunak is facing calls from charities, campaigners and even some of his own MPs to cancel the planned cut.
Outlining the case, Shadow Work and Pensions Secretary Jonathan Reynolds said axing the rise “would be fundamentally the wrong decision”.
He told MPs: "It would be a profound mistake for families, for the economy and for our ability to effectively tackle and recover from the Covid pandemic."
Mr Reynolds said he was not there to claim Tory MP were "heartless or lack compassion" - and said no MP should be abused after the debate.
He also confirmed Labour's view was Universal Credit should be replaced but the party did not plan to "abolish the welfare state" as Tory attack videos claimed.
Treasury minister Steve Barclay said the Government is "acutely aware" of the harm caused to finances by the Covid-19 pandemic.
"It's clear that there is a heartfelt desire shared across all sides of the House to support constituents impacted by the economic consequences of Covid," said Mr Barclay.
"As a government, we are acutely aware of the harm caused by the crisis to people's finances including the most vulnerable in our society.
"At every stage of the pandemic, we have striven to support those who have found themselves at the sharp end."
He said it was right to wait until the Budget to make a decision, and pointed to welfare support worth over £7billion this year.
But a number of Tory MPs broke ranks to criticise ministers for failing to extend the lifeline.
Former Work and Pensions Secretary Stephen Crabb said: “The uplift is so important right now and ... it needs to be extended for a further 12 months."
He added: "The question for us right now is whether at the end of March this year, just 10 weeks away, it's the right time to begin unwinding this support - specifically to remove the extra support for Universal Credit claimants - and I don't believe it is the right moment."
Barrow and Furness's Simon Fell said: “Now is not the time to consider any reduction in the uplift in Universal Credit.
"This uplift was brought in to help people through the extreme challenges of the pandemic and those challenges haven't passed.”
Carlisle MP John Stevenson said the Universal Credit increase had been a "life-saver" for people through the pandemic.
He urged the Chancellor “to extend the Universal Credit uplift until restrictions are lifted, to ensure that individuals and families who have been worst affected by this pandemic are supported through our recovery with the security they need”.
Earlier, Mr Johnson repeatedly refused to say whether the uplift would continue.
Speaking on a visit to Oxfordshire, he said the Government wanted to make sure "people don't suffer as a result of the economic consequences of the pandemic".
He insisted: "What we have said is we will put our arms around the whole of the country throughout the pandemic.
"We have already done £280 billion worth of support and we will keep all measures under constant review."
No10 tried to quell the rebellion by signalling Mr Sunak, who is due to deliver a Budget on March 3, was poised to act “in the weeks to come”.
The PM's press secretary Allegra Stratton said: "We know it runs out at the end of March, we know that households want to know what is coming next and he is going to come forward with more information shortly."
Earlier, a Tory minister triggered fury by accusing Labour of staging “a political stunt”.
Business Minister Nadhim Zahawi said: “This debate today has no real impact on the outcome on those families, other than a political little stunt for Labour."
But Labour leader Keir Starmer told ITV's Lorraine: "If he's going to call it a stunt, he should probably come with me to a food distribution centre to see these families this morning and explain to them what is a lifeline to them is a 'stunt', because it certainly isn't from their point of view.
“I actually think in their heart of hearts quite a lot of Tory MPs know that cutting this money to people who desperately need it in the middle of a pandemic is the wrong thing to do, they know that, they probably want to vote with us but because of the tribal way we do politics they can't.”
York University’s Dr Ruth Patrick, who is leading the Covid Realities research programme, said: “The decision on whether to continue the £20 uplift to Universal Credit will affect millions of households.
“The Government needs to listen much more carefully to what these households are saying about the everyday hardship they are experiencing and about what particular financial pressures they face.”
Save the Children's head of child poverty Becca Lyon said: “Something has gone seriously wrong if we’re talking about taking money away from struggling families in the midst of a pandemic.
“We urge the Government to keep the uplift to Universal Credit, which has been a lifeline for struggling families, and make a clear commitment to families that they and their children won’t be facing an even tougher time than they are at the moment.”