Moderate government MPs are urging Malcolm Turnbull to act now in order to be favourably remembered as the Liberal Prime Minister who made same-sex marriage a legal reality in Australia.

But with the apparent death on Tuesday of the Coalition’s plan for a costly plebiscite on marriage equality, the issue seems all but doomed – at least for this term of parliament.

Opposition Leader Bill Shorten has blocked the plebiscite, saying his caucus voted unanimously to deny the enabling legislation for a poll to be held on February 11.

Instead, Labor is calling for a free parliamentary vote in order to avoid a near $200 million cost and a potentially ugly public debate.

“The experts have unequivocally explained to Labor that the plebiscite would cause harm to gay and lesbian people – particularly, but not exclusively, young people,” Mr Shorten said.

“Having met these families, having listened to their stories, I could not in good conscience recommend to the Labor Party that we support the plebiscite about marriage equality.

“The Labor Party, therefore, will in parliament oppose Malcolm Turnbull’s expensive, divisive plebiscite.”

In parliament, Mr Turnbull would not back down, insisting the Australian people should have their say and were capable of a civil debate.

The bill will pass in the House of Representatives this week, but will be blocked in the Senate where Labor, the Greens, the Nick Xenophon Team and Derryn Hinch will join in voting against it.

“We are delivering on our commitment to the Australian people to bring a plebiscite before the parliament,” the Prime Minister said.

“I’m not going to go follow Bill Shorten down his highly political road of trying to subvert a straightforward democratic process, of trying to say to the Australian people you shouldn’t have a say.

“Mr Shorten supported a plebiscite of this kind only three years ago.”

Paradoxically, although Mr Shorten is demanding the Prime Minister allow Coalition MPs a free vote on the issue, Labor MPs are bound by party rules to vote in favour of same-sex marriage.

Mr Turnbull, however, is unlikely to agree to a simple parliamentary vote.

Although he is personally in favour of marriage equality, he is allowing himself to be shackled by the conservative wing of the government.

One Nationals MP, Andrew Broad from Victoria, has already begun acting like an independent, threatening to withdraw support for the government should there be a vote in parliament without a plebiscite being held first. 

Nationals MP Andrew Broad will provide opposition from within if Turnbull wants action on same-sex marriage. Photo: AAP

“The government that I am a part of, and will remain a part of, is conditional upon the fact that the only way that there will be a change to the Marriage Act in this parliament is a plebiscite,” the Member for Mallee said.

“I’m making it very clear here, my support for the government is that we honour our election commitment, that we ask the Australian people for their say on this issue.”

But while the ultra-conservative MPs are publicly demanding the plebiscite go ahead, yet quietly rejoicing over its demise, others inside the government see it as an opportunity.

Equal marriage proponent Warren Entsch is already on the record saying he prefers a parliamentary vote.

Tanya Plibersek celebrates with anti-plebiscite campaigners after voting to block the legislation. Photo: AAP

Others are joining him behind the scenes and suggesting Mr Turnbull could go down in history for the right reasons.

“The Prime Minister could stand up to the bullies in our ranks and do the right thing,” one Liberal MP told The New Daily.

“If he were to be the Prime Minister to bring same-sex marriage into the parliament – and a Liberal Prime Minister at that – his legacy would be sure.” 

Another agreed, saying the opportunity was there for the taking.

“But making history is not for the faint of heart,” the MP said.

More likely, however, is the Prime Minister and government do nothing once the plebiscite bill goes down, leaving it to the opposition to keep calling for a parliamentary vote on marriage equality – which will probably not happen until Labor wins power.