A report has warned that around a fifth of Universal Credit claimants fear they will need to use a food bank or will fall behind on housing costs if the £20 weekly increase is not kept in place past March.
Research from Christian charity Trussell Trust, which runs a network of foodbanks across the country, found that one in five people receiving the benefit said they are "very likely" to need to use a food bank if the uplift is cut - the equivalent of 1.2 million people.
And 19 per cent said they would be very likely to fall behind on housing costs, such as rent or mortgage payments.
The Government has not said whether the temporary increase, introduced at the start of the pandemic and in place until the end of March, will be extended.
It has been described as a "lifeline" for struggling families, and the Trussell Trust says it has prevented tens of thousands of people from turning to a food bank.
The Trussell Trust's polling of 1,000 adults between January 19-25 found that 41 per cent of Universal Credit claimants fear they will be very likely to cut back on food for themselves if the cut goes ahead.
This is the equivalent of more than 2.4 million people across the UK when extrapolated to population level.
And 13 per cent of respondents - representing more than 220,000 families - think they would be very likely to cut back on food for their children.
Emma Revie, chief executive of the Trussell Trust told Premier Christian News: “I think the fear of being unable to feed our families is awful,” she said.
She added: “One of our respondents [to the survey] said ‘I don't want to think about it, life is difficult as it is with the extra £20. Without it, I fear for my kids’ well-being. I'm so tired of struggling and worrying about basic survival’. And we see hundreds of thousands of people finding themselves in that situation.”
The Trussell Trust joins a host of organisations, including charities and the Work and Pensions Committee, in calling on the Government to extend the uplift beyond March.
It is urging the Government to make the increase permanent, or at the very least maintain it for a further year, and to extend it to people receiving legacy benefits.
Seven in ten claimants said the uplift has made buying essentials easier, it added.
"This survey reveals the shocking consequences of what lies ahead if this lifeline is cut in April,” Revie said.
"This isn't right. No one should have to suffer the indignity of relying on emergency food.
"It's clear that action is needed to ensure our benefits system provides people with enough money to cover the essentials.
"That's why we're insisting the Government turns this situation around. Keeping the £20 Universal Credit uplift, and extending it to legacy benefits, will provide an anchor from poverty for people who need it most.
"The Government should continue to do the right thing and keep this lifeline. It is a crucial step in moving towards a hunger-free future for the UK."
A Government spokesman said: "We are committed to supporting the lowest-paid families through the pandemic and beyond to ensure that nobody is left behind.
"That's why we've targeted our support to those most in need by raising the living wage, spending hundreds of billions to safeguard jobs, boosting welfare support by billions and introducing the £170 million Covid Winter Grant Scheme to help children and families stay warm and well-fed during the coldest months."
Listen to Premier’s interview with Emma Revie here: