Thousands of private renters who have lost their jobs could be facing eviction when the coronavirus lockdown ends, the government has been warned.
Almost half a million people are at "high risk" of homelessness, according to 187 local councils across England.
And charity Shelter says first time benefit claimants face falling behind with payments and ending up in debt.
The government has made housing benefits more generous to help those most in need during the pandemic.
It has also suspended evictions for the duration of the crisis.
But Shelter says many of the nearly two million people who are applying for universal credit to help them through the crisis are finding that it does not come close to covering their rent.
Many are in a double bind because they can't move to cheaper accommodation, or get a new job, due to the lockdown.
The charity is calling on the government to temporarily increase the housing element of the benefit - the Local Housing Allowance - to match 50% of the average rent in an area.
At the moment, payments are based on the bottom 30% of rents in an area.
'It is not my fault I have lost my job'
Amy Corker, 32, lost her job as an account executive at a printing firm, when the company was forced to lay off staff just before the start of the lockdown.
She applied for universal credit to cover the £425 a month rent on her two-bedroom house in Barnsley, South Yorkshire, but was "shocked" to receive just £141 in total, including housing allowance, and minus three days pay from her final wage, for the month. Her landlord, who knew she was struggling, waived her rent for a month, but she has now run out of money.
"I have always paid my rent. I have always paid my bills," said Amy.
"It is not my fault I have lost my job if I didn't have an understanding landlord I don't know what would have happened. I don't know what's going to happen next month."
Amy, who had only started her job at the printing firm in January, is now doing a commission-only telesales job from home and is trying hard to find another full-time role.
"I am coming to terms with it. That this is what is. But these past seven weeks have been immensely tough mentally. Sometimes I can laugh about it. Sometimes I get really upset and emotional. I start thinking 'am I going to have pack everything up and leave?', or will I be able to find a job and stop that?"
Shelter says hard-hit renters relying on universal credit must find an estimated £13m a week in total to keep up with their rent payments, which could add up to a £660m black hole in their finances over the next 12 months if the government fails to act.
Chief executive Polly Neate said she hoped the government would listen because the country needed people to get back on their feet to help economic recovery, rather than being crippled by debt and insecure accommodation.
"With just a bit of help, they can ride out this crisis, they get can get a new job, and move somewhere cheaper.
"Without that help, we are just going to see a tsunami of evictions once the lockdown ends."
'Over the edge'
Ms Neate is delivering a 140,000 signature petition, compiled jointly with campaign site 38 Degrees, to Downing Street on Thursday, calling on the chancellor to take action.
The District Councils Network has, meanwhile, produced research which suggests more than 486,242 households are spending over half their income on private rented housing, and which could be at risk when the evictions ban is lifted.
The network, which represents 187 local authorities in England, says lone parents with children, young people and households on low incomes are particularly in danger of being tipped "over the edge" into homelessness.
It is calling for a permanent boost to housing benefits for those in private rented homes, and more funding for councils to fight homelessness, build homes and create jobs.
Councillor Giles Archibald, the network's Better Lives spokesman, said: "The government has already rightly acted to support businesses and residents, but to avert a huge rise in homelessness it must now put the housing crisis at the centre of its exit strategy and recovery effort to support people as the scale of the economic impact becomes clearer."
A government spokesperson said: "We're committed to supporting all those affected by Covid-19 through these unprecedented times and we've implemented an enormous package of measures to do so.
"We've injected more than £6.5bn into the welfare system, including helping over one million households by raising Local Housing Allowance rates for universal credit and housing benefit claimants.
"And we've increased protections for renters to prevent evictions due to difficulties caused by Covid-19.
"We've also provided £180m in Discretionary Housing Payments to local authorities this year to further support those most in need."
Communities Secretary Robert Jenrick said at Wednesday's Downing Street press conference the government would ensure councils "have the resources that they need to carry out the absolutely critical functions that they are playing in our national response to coronavirus".