Prime Minister Anthony Albanese has issued a stern warning to opponents of a plan to increase affordable housing, saying its defeat will not be a loss for the government but for vulnerable Australians.
The government's signature $10 billion housing fund faces a battle to pass the upper house, with the Greens demanding further measures to ease the property squeeze.
Mr Albanese, who grew up in social housing, said Australians had voted for the government to take action on the crisis.
He warned parliament a vote against the proposal was a vote against funding for more social and affordable housing.
"If you're determined to vote against this and somehow say that this is a defeat for the government, it's not," he told parliament.
"It's a defeat for people who need a secure roof over their head.
"Be prepared to say that you had the chance to help and you chose to say no."
The coalition intends to vote against the proposal, but outspoken Liberal backbencher Bridget Archer signalled she may break ranks with her party to support it.
She said there was a social and affordable housing crisis in her home state of Tasmania and she wanted to be "part of the solution".
But the Greens hold the keys to getting it through the Senate.
The minor party wants a minimum of $5 billion invested in social and affordable housing every year.
They argue the 30,000 homes to be built over five years are well below what is needed and the $500 million annual spending cap is too restrictive.
Greens leader Adam Bandt said to secure his party's support, the government needed to "do better" on housing, including a much greater investment in social housing and measures to help renters.
"Renters need this bill to be better, First Nations communities need it to be better, everyone who is struggling to put an affordable roof over their head needs this government to do better," he said.
But Mr Albanese said the Greens' demands were "fantasy" as skills shortages and supply issues would not deliver what they promised.
"The idea that you would pass legislation knowing that you can't possibly achieve the outcome is the ultimate self indulgence, the ultimate virtue signalling which will not have any impact at all," he said.
"We always had been prepared to consider constructive amendments, ideas ... but let's not just chuck out figures from the backs of envelopes and written on a coaster."