Taoiseach Brian Cowen was today urged to pour €4 billion into social housing for thousands of people on waiting lists.
Trade unionists and homelessness campaigners insist the cash is needed to build 18,000 houses next year to make up an accommodation shortfall.
Siptu, Ictu and Focus Ireland came together to deliver the joint demand in a pre-Budget submission to the Government.
Jack O'Connor, Siptu president, said the gloomy economic prospects made it all the more vital for money to be set aside for the social sector.
"It is crucial that the Government takes steps in next week's Budget to radically increase the supply of social and affordable housing," he said.
Some 10,000 social homes, 6,000 affordable homes and 2,000 new rental accommodation homes are needed next year to meet demand, according to the organisations.
"The boom in the Irish economy was of little consolation to those on social housing waiting lists or people who are homeless," said Mr O'Connor.
"The need for action is now even all the greater now given the more difficult economic circumstances faced by many."
But Mr O'Connor hit out at calls from developers who are also demanding the Government earmark cash for increased social housing.
"Let us be clear, this cannot be a generous injection of good fortune to relieve the woes of property developers and the wider industry at this time," he said.
"Such contracts have to be negotiated on terms that are sufficient to cover building costs and that respect the industrial pay rates and ensure fair and decent working conditions."
He added: "The drastic downturn in all areas of construction has dealt a devastating blow to over 30,000 workers and there is now an even stronger argument to be made for the increase in social housing output, to deploy the spare capacity of building skills to a sector most in need of it."
Joyce Loughnan, Focus Ireland's chief executive officer, said there was both a strong social and economic case for investment in social and affordable housing.
"A focused programme of new build and acquisition of social and affordable housing in the order of 18,000 units a year for a number of years would act to stabilise the economy in the short term and at the same time meet growing housing needs, particularly for people who are homeless or at risk of becoming homeless," she said.
If the Government is able to give the banks a €400 billion guarantee, then it must be able to set aside €4 billion to provide homes for those most in need, she added.
PA