Australia’s Attorney General has threatened that reform on same-sex marriage will be delayed until 2020 if the government’s public vote plan is blocked.

The country’s PM Malcolm Turnbull is trying to avoid a rift with his own ultra-conservative MPs by bringing forward plans to take same-sex marriage to the public in a non-binding plebiscite, instead of settling the matter in Parliament.

However, opposition parties are lined up against the $200 million plebiscite – with the draft plebiscite bill even handing $7.5 million of funding to anti-LGBT activists to run a ‘No’ campaign.

As the government does not have a majority in the Senate, its plebiscite bill is expected to be shot down – with many LGBT activists hoping for a compromise to quickly pass the issue through Parliament instead.

But the country’s Attorney General has threatened a four-year delay on the issue if the plebiscite is shot down this month, after negotiations broke down.

After peace talks with the opposition Labor Party collapsed, Attorney General George Brandis has warned: “My fear is that if the Labor Party blocks what is now the only feasible course for progressing this issue in this Parliament, the issue will go off the boil and we won’t know for how many years it will be that marriage equality is denied to same sex couples.

“The government is prepared to negotiate with the Labor Party in good faith because we are committed to resolving this matter by a plebiscite. That was endorsed by the Australian people at the last election.

“And if, like me, you favour reform to the Marriage Act to allow same-sex couples to marry then this is now the only feasible path to that outcome for many years to come.”

But his Labor opponent says that zero concessions were offered by the government during negotiations.

Shadow Attorney General Mark Dreyfus said: “The Attorney-General did not suggest anything that the Government is prepared to change.”