The opposition, along with many gay rights campaigners, favours a free vote among MPs, with parliamentarians not bound by party policy.
They have also argued about timing, costs and the scope of possible campaigns for and against same-sex marriage, even as a good deal of the negotiating has taken place away from public view.
Prime Minister Malcolm Turnbull has ruled out further action on same-sex marriage if the High Court strikes down the government's national postal ballot.
"Strong leaders carry out their promises, weak leaders break them", Turnbull told reporters.
If the postal vote goes ahead and shows support for changing the law, the results will not be legally binding.
Q When will the vote take place? The cost would have been 170 million Australian dollars ($135 million).
A final result is expected to be released by November 15th.
Crespo tips Man United to win Premier League
United's focus this year will be very much on winning the physical battles and pretty football patterns will have to wait. Guardiola will hope the well-publicised woe of Claudio Bravo has been addressed with the signing of Ederson from Benfica.
Carabao Cup confusion as second-round draw leaves clubs baffled
For the second time running the draw was shrouded in confusion - it was not initially clear which team were drawn at home. Arsenal, Chelsea, Everton, Liverpool, Manchester City, Manchester United and Tottenham join in the third round.
The important role casinos played in the life of Glen Campbell
By the late '60s, he was a performer on his own, and an appearance on Joey Bishop's show led to his TV breakthrough. Ashley Campbell , Glen Campbell's daughter, shared family photos and a letter to fans on Friday (Aug. 11).
Others, like Joel Smith from Melbourne who arrived in the United Kingdom in June, aren't going to vote. Equality advocates and supporters are opposed to a nationwide plebiscite, saying civil rights should not be subject to a popular vote.
Sharing a video to Facebook, the comedian re-writes Peter Allen'sI Still Call Australia Home, taking aim at the government and postal plebiscite that is likely to take place, encouraging Australians to vote in the postal poll in an effort to legalise same-sex marriage. The Bill needs to pass both the Upper and Lower Houses to be made a law.
Q Who will conduct the ballot?
Mr Shorten told Parliament that while Labor, along with the majority of those who support change, deemed the $122 million postal ballot wasteful, non-authoritive, unnecessary and hurtful to gay and lesbian people and their families, it was important the No vote did not prevail.
"If you're anxious about religious freedom and freedom of speech, vote "No", and if you don't like political correctness, vote "No" because voting "No" will help to stop political correctness in its tracks", Abbott told reporters outside Parliament Wednesday morning.
"Why are we spending money we could use on making this country better on something that shouldn't necessarily need to be a vote?"
Instead it would be spent on a useless opinion survey given that conservative Liberal senators, such as Eric Abetz, have indicated they will not change their vote regardless of the outcome, she said.