Conservative cabinet minister Eric Abetz says Australia should not legalise gay marriage because no Asian country has adopted marriage equality.
And Senator Abetz says legalising gay marriage would lead to polyamory and argues issue should be rejected out of hand because Opposition Leader Bill Shorten supports change.
In his first comments since returning from a long period of personal leave, Senator Abetz launched an attack on the campaign to legalise same-sex marriage in Australia, which has been bolstered by the recent Irish referendum and US Supreme Court ruling.
Two Liberal MPs have been revealed as co-sponsors of a multi-party private members bill due to be introduced into the Parliament in August, meaning the issue can finally come to a head in the Liberal partyroom.
Many Liberals favour change and want a free vote but the conservative wing of the party mobilised on Thursday to warn the support required to pass any bill into law does not exist within the government.
Supporters of change say Australia is now lagging the rest of the world, with comparable countries including Britain, New Zealand, America and Ireland all redefining marriage to include gay couples.
But Senator Abetz questioned whether Australia should instead be following Asia on the issue.
"The Labor Party and other journalists tell us time and time again that we are living in the Asian century, tell me how many Asian countries have redefined marriage?" Senator Abetz said during an interview on ABC radio.
He also lashed out at the "bizarre" US Supreme Court decision and pleaded for "some rationality and balance back into the debate".
"Are we in the Asian century or not? It's amazing how certain people try to pick and choose in relation to debates. All of the sudden the United States, which is usually condemned, is now being celebrated on this bizarre decision of a 5-4 decision in the Supreme Court."
Appearing on Sky News a short time later, Senator Abetz described the push for marriage equality as "the latest fad".
"If you undo the institution of marriage by redefining it for the latest movement or the latest fad, you will open the Pandora's box," he said.
"Like what?" asked host Kieran Gilbert.
"Well polyamory clearly, polamory is one of those….let's not be under any illusion that once you start unpicking the definition of marriage, there will other consequences," Senator Abetz replied.
Senator Abetz's comments are reminiscent of when fellow right-wing senator Cory Bernardi said same-sex marriage could lead to acceptance of bestiality. He was subsequently sacked from his shadow frontbench role.
Senator Bernardi renewed his warnings on Thursday that gay marriage would deny children what he said is their right to a mother and a father.
"If you are claiming this is an issue of discrimination, who are you to discriminate from you know, commercial surrogacy? Aren't you then denying someone the opportunity to have children or to enter into private arrangements in that capacity?" he told the ABC.
Senator Abetz also opposed same-sex marriage on the basis that it is supported by Mr Shorten.
He also slammed the Australian media and said voters resented "unfair reporting" by journalists on the issue.
"I don't think Australians want it, it's not a high order issue," he said.
Prime Minister Tony Abbott on Wednesday slapped down a cross-party attempt to legalise same-sex marriage.
The debate over same-sex marriage will come to a head when Parliament resumes in August, with a marriage equality bill moved by Liberal MP Warren Entsch and seconded by Labor MP Terri Butler and backed by a multi-party grouping to be introduced.
But Mr Abbott pushed back on Wednesday against the move, saying through a spokeswoman that his position remained unchanged and that the government's priority is the economy and national security.
