Any funding for the yes and no cases in the same-sex marriage plebiscite would be given in a "scrupulously equal and fair" way, Malcolm Turnbull insists.
As Labor and crossbenchers brought private bills to parliament on Monday to change marriage laws, cabinet was due to sign off on the details of a plebiscite.
The coalition joint party room was due to discuss the cabinet decision on Tuesday before an enabling bill goes to the parliament.
Labor opposes the plebiscite, which is expected to cost at least $160 million, and does not want taxpayers' money spent on the yes and no cases.
Sydney Anglican Archbishop Glenn Davies is adamant Mr Turnbull gave an "unambiguous" assurance to religious leaders funding would be made available to both sides of the argument.
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Dr Davies also says Attorney-General George Brandis, at a meeting in March, had asked what amount of funding was considered appropriate by religious leaders, to which Senator Brandis was told the same amount as the 1999 Republic referendum, adjusted to CPI - about $10 million.
Senator Brandis told reporters on Sunday both sides of the argument would be treated equally if there was public funding.
Opposition Leader Bill Shorten asked the prime minister in parliament on Monday whether he had made it clear it was a matter for cabinet or told religious leaders the funding was guaranteed.
Mr Turnbull said he would not discuss private conversations.
"The government's position and my position has always been this - that any funding provided to the 'yes' or 'no' case will be scrupulously equal and fair, as it always has been with respect to referendums in the past," Mr Turnbull said.
"The details, nature and amount, terms of any such funding and the terms of the plebiscite are a matter for the cabinet ... then it will be presented through the party room processes and following that to the parliament. "
Liberal backbencher James Paterson, who supports gay marriage, said neither side should be given taxpayer funds.
"If we can't think of a better way to spend taxpayers' money ... we're not doing our jobs," he told parliament.
However, conservative senator Eric Abetz said public funding had been part of the plebiscite decision by the party room last year and cabinet should not seek to "steamroll" MPs.
Greens MP Adam Bandt, who moved a crossbench bill, said it was "the equivalent of funding the schoolyard bully to go and insult other students".
Media reports suggest the favoured date for the vote is February 11.
In introducing Labor's bill, Mr Shorten said he was happy to back a bill from the government or crossbench if necessary.
"What will stand for all time is this parliament's statement that marriage is about love not about gender," Mr Shorten said.
