It was barely a month ago that this looked like pretty much a done deal. The battle over gay marriage in Australia has been, if anything, even more contentious than it was in the United States. But after years of wrangling and failed attempts at compromise, there was going to be a plebiscite (or public referendum done by mail-in ballots) in September to determine the future of such unions.

Not so fast there, Aussies. The entire process is being challenged and the nation’s highest court is taking up the question. The truly curious part of this is that it’s actually the supporters of gay marriage who are the ones trying to shut it down. (Reuters)

With the non-compulsory vote a couple of weeks away, its opponents have launched a legal challenge, saying the vote needs the backing of parliament – which has twice rejected such a national ballot.

“This case is about dignity and equality for lesbian, gay, bisexual, transgender and intersex Australians,” Anna Brown, director of legal advocacy at the Human Rights Law Centre, which leads the opposition to the vote, told reporters in Melbourne.

“We’re here because we all believe and want marriage equality. This postal plebiscite has big question marks around its legal validity.”

Conservative lawmakers have threatened to resign if the ballot policy is not adhered to, risking Turnbull’s parliamentary majority.

As far as both public opinion and a majority of members of Parliament are concerned, gay marriage is already pretty much a done deal. Polling shows a significant majority of voters are in favor of it and there are more than enough members of Parliament willing to sign on. Even Prime Minister Malcolm Turnbull is a supporter. So what’s the hold-up?

Mirroring many situations in the United States, it all comes down to politics. Turnbull currently holds on to his leadership position by the slimmest of margins… only a single seat in Parliament. His ruling coalition includes some hard core conservative groups, however, and they’re threatening to bolt if this policy goes through. That’s how the plebiscite got rolling in the first place. If Turnbull could turn it over to a direct vote by the people then he wouldn’t have to have his name attached to it and could simply shrug his shoulders and claim Vox Populi, Vox Dei if the conservatives complained.

But now the supporters of gay marriage are bucking against the plebiscite because they fear a last minute surge of negative advertising could tamp down public support and cause the measure to fail. They would prefer a straight-up vote in Parliament through the regular order where they are confident of having more than enough support. There’s also a question of whether or not the plebiscite can even be considered binding.

They have a couple of weeks to sort it out, but one thing is certain. No matter which way it goes, Malcolm Turnbull’s tenure as Prime Minister is riding on a razor edge right now and he may be on his way out.