Shelter said affordable housing must be made a priority
Housing campaigners have called on MSPs to review the cash for affordable homes after spending was cut in the Scottish Government's budget.
Shelter Scotland claimed investment in housing was the "main casualty" in the draft budget unveiled by Finance Secretary John Swinney on Thursday.
The charity's director, Graeme Brown, said housing costs, such as land, were lower and builders needed the work.
The Scottish government said it had spent £1.5bn on housing in three years.
A government spokesman also called for Westminster to release more funds to allow accelerated spending.
Mr Brown called on MSPs to "seize the opportunity" to invest in housing.
The money to be spent on affordable housing will go down from £525m this year to £352m next year.
Part of that reduction, according to budget documents, is caused by the fact £120m of spending already brought forward will have to be repaid next year.
But Shelter Scotland said that when cash for Edinburgh and Glasgow for housing was taken into account, along with money that came to Scotland as a consequence of Westminster spending decisions, there was a total of £675m for affordable housing this year.
However it claimed that next year there would be £471m for the sector - the £352m in the budget plus £119m for housing in Scotland's two main cities.
And it argued that meant a drop in spending of more than £200m.
Mr Brown warned: "The publication of the draft budget is just the start of a long process. The battle for more housing cash is not over."
He added: "What could be more efficient than buying land when prices are low? Or employing building workers who otherwise lose their jobs?
"It is precisely because housing investment is so efficient that I appealed for this to be a Budget for homes. MSPs need to seize that opportunity.
"Instead, at a time of record numbers stuck in temporary accommodation and rising house waiting lists, we see the brakes slammed on housing spending next year."
A Scottish Government spokesman said: "If the UK government allows accelerated capital spending into 2010-11 from the following year, more housing resources can be delivered by the Scottish Government next year.
"We hope the UK government will announce a capital acceleration in the November Pre-Budget Report, as we have been requesting."
He continued: "Despite the tightest settlement from Westminster since devolution, this government has been pulling out all the stops to increase the supply of affordable homes, backed by more than £1.5bn over three years."