The director of advocacy group Australian Marriage Equality says a plebiscite on same-sex marriage is "unnecessary" and "harmful," following a report that estimated such a move would cost more than $500 million.
"It's unacceptable for more than half a billion dollars to go towards a national opinion poll that is not legally binding, some politicians have already said they'll ignore, and some groups are using as an excuse to call for the suspension of anti-discrimination laws," Mr Croome said in a statement.
The comments come following the release of a report from accounting firm PwC Australia, which found a compulsory vote on marriage equality would cost the Australian economy $525 million.
It estimates that a plebiscite not held on the same day as a federal election would cost the taxpayer $158 million to organise, $66 million for the community to fund the for and against campaigns and $281 million in lost productivity as people take time out to vote.
There would also be least $20 million in costs associated with the impact on the mental health and wellbeing of Australians.
Conservative senator Eric Abetz today labelled the study "skewed".
Senator Abetz, who is strongly opposed to same-sex marriage, claimed calculating lost productivity when people would be voting was "bizarre", but failed to provide any evidence beyond this about the costs.
He also noted the study did not take into account the costs on the other side of the debate, to people who will feel depressed about change.
"I think this is a very skewed study," he told ABC radio.
"It does show and indicate that this was a study in inverted commas with an outcome that was sought by those doing it."
PwC Australia CEO Luke Sayers said the real cost of holding a stand-alone plebiscite is more than three times higher than the numbers commonly quoted.
The modelling which the company undertook of its own volition and was not commissioned by another third party, showed the plebiscite would be a drain on the economy and bad for business, calling instead for a parliamentary vote as the best mechanism for change.
"It's clear from these findings that a stand-alone plebiscite on marriage equality is a massive waste of time and money that will remove focus on the economy, growth and jobs which is the real priority for Australia."
The modelling costed three parliamentary mechanisms, including the stand-alone plebiscite costing $525 million.
It found a plebiscite at the next federal election followed by a parliamentary vote would cost $113 million and a parliamentary vote involving campaigning but no plebiscite would cost only $17 million.
Labor seized on the "staggering" cost of a stand-alone poll, saying parliament could just do its job and legislate for change immediately.
"Clearly, this is the price Malcolm Turnbull will make all Australians pay for the deal he did with the conservatives in his party to become prime minister," Bill Shorten said in a joint statement with colleagues.
Senator Abetz expects the plebiscite to be held in the first 12 months of the next government.
Mr Croome called on the public to lobby members of cabinet to stop the plebiscite going ahead.
“The damage an ugly and divisive campaign will do to vulnerable members of the LGBTI community, their families, and youth will have far-reaching consequences that cannot be quantified,” he said.
