Nearly half of working private renters in England could not afford their rent for more than a month if they lost their job, Shelter has found.
Some 45% of people surveyed for the charity said they would be in this position.
Shelter said that if the findings were projected across the country nearly three million private renters could be just one pay cheque away from losing their home.
Among working families with children, the charity found 60% could be just one pay cheque away from losing their home.
With current political and economic uncertainty, the charity is urging all political parties to ensure social housebuilding is at the centre of any domestic agenda.
Polly Neate, chief executive of Shelter, said: "Millions of working people are now caught in an endless cycle of paying grossly expensive private rents they can barely afford - with all the insecurity that brings.
"Many are terrified that even a short-term dip in income could result in them losing their home for good.
"Warm words and piecemeal policies will not solve this deepening crisis.
"The only way politicians can fix what has gone so wrong is with a clear commitment from every party to deliver three million more social homes over the next 20 years."
More than 3,900 private renters across England were surveyed.
Shelter quoted a 44-year-old single parent who said: "Life is hard, but I know it's the same for thousands of other people like me.
"When you scratch the surface so many people are living month to month - 'robbing Peter to pay Paul'."
