Crisis is opening temporary shelters for the homeless over Christmas
Homeless charities' Christmas campaigns have begun amid fears the new year could see homelessness surge.
In London, homeless children are handing over 5,000 baubles to Downing Street bearing messages calling for more affordable housing to be built.
The charity Shelter asked people across the country to sign the baubles.
Meanwhile, a survey for Crisis, another homelessness charity, suggests nearly one in 10 people are struggling to keep up with rent or mortgage payments.
The YouGov online poll of 2,015 adults showed of those questioned who expressed an opinion, about a third (32%) said they would lose their home within three months of losing their main income.
It also found that 41% knew somebody who had lost their job due to the economic downturn.
And 28% of people in lower income groups said they were worried they could lose their home due to the economic crisis, compared to 21% of people in higher income groups.
The findings come as Crisis opens nine temporary centres across London for hundreds of homeless or vulnerably housed people.
The centres, which will stay open for a week, provide companionship, hot meals and shelter as well as housing services, job advice, health checks, training and further education opportunities.
Leslie Morphy, chief executive of Crisis, said: "The economic downturn is hitting the poorest the hardest.
"Many are struggling to keep their homes. The situation is only made worse by pressure on jobs, with unemployment levels set to reach two million by the end of the year.
"Our fear is that as the recession bites in the new year we are going to see more people in the same situation as those relying on our Christmas centres today, whilst those already at the bottom of the pile are going to be further away from the help and support they need to put their lives back together."
Her concerns are shared by Shelter's chief executive, Adam Sampson.
He said: "With repossessions soaring, thousands stuck on council housing waiting lists and hundreds of homeless households trapped in temporary accommodation, it seems everyone is feeling the effect of the current housing crisis this Christmas.
"We hope Gordon Brown will listen to the public and keep his promise to build the homes Britain desperately needs."
The charity said the campaign already had the support of 5,000 people, including Conservative MP Iain Duncan Smith and Labour MP John Battle.
A Communities and Local Government spokesman said record amounts were being invested to prevent and reduce homelessness.
He added: "We are determined to give families real help in the current economic climate and do everything possible to help ensure repossession is always a last resort.
"We have already introduced a £200m mortgage rescue scheme to help vulnerable families remain in their homes, expanded free debt and legal advice, and are working urgently on the recently announced new support to help hard working households if they suffer a loss of income.
"We are also taking action to maintain the delivery of affordable homes by bringing forward £550m to provide more social housing sooner for families in housing need and we are investing in buying up thousands of unsold homes off the open market to use as affordable housing."