Former prime minister John Howard has criticised the Turnbull Government's handling of the same-sex marriage survey, calling for the details of any bill to be released before the vote.
In a statement, he said the Government was "washing its hands of any responsibility" to protect religious freedoms should the survey come back with a majority Yes vote.
Malcolm Turnbull has repeatedly said the Parliament will change the Marriage Act before the end of the year if there is a Yes vote, but hasn't provided any more details.
Liberal senator Dean Smith and a number of backbenchers have prepared a private members bill, but it is not confirmed whether this is the bill that would be introduced.
Mr Howard said the Government needed to spell out what steps would be taken to protect parental rights, freedom of speech and religious freedoms.
He said there would be overwhelming pressure to legislate quickly given the Prime Minister had already set a deadline, leaving "scant opportunity" to debate the protections.
"Very likely, those raising such matters will be met with a chorus of put-downs, and accused of attempting to frustrate the verdict of the people," Mr Howard said.
"Thus far, the Government's response has been to wash its hands of any responsibility, merely stating that it will facilitate a private member's bill.
Mr Howard also criticised those in the Yes campaign who dismissed concerns about religious freedoms as so-called "red herrings", saying there were "legitimate concerns".
"It is completely disingenuous to assert that a change of this magnitude to a fundamental social institution does not have consequences," Mr Howard said.
"It is precisely because parliament should reflect the will of the people that the people are entitled to know what, if anything, the Government will do on protections before they vote. Otherwise, people will not be fully informed when they vote."