Prime Minister Malcolm Turnbull isn't committing to a national vote on same-sex marriage this year, instead saying one will be held as soon as possible after the election.
Attorney-General George Brandis on Sunday said if the government was re-elected there would be a plebiscite this year, sparking speculation about the planned timing of the election.
But the prime minister's office is sticking to its existing position, with a spokeswoman telling AAP it would be held "as early as possible after the election".
Malcolm Turnbull speaks about the Mardi Gras parade:
The Australian Electoral Commission has told a parliamentary inquiry it would need 29 weeks to plan a plebiscite, meaning holding one this year would likely require an early election.
"The bill to constitute the plebiscite will be introduced early in the life of the new parliament so that we can have the plebiscite before the end of this year," Senator Brandis told Sky News on Sunday.
Opposition Leader Bill Shorten said the incident proved the chaos and division within the Liberal government.
"This is a new land speed record for a broken promise, made over breakfast and gone before dinner," he said in a statement on Sunday.
"If his own attorney-general can't rely on Malcolm Turnbull, how can Australians?"
Senator Brandis had no doubt that if the public voted 'yes', parliament would follow the will of the nation.
Participants are seen taking part in the 38th annual Gay and Lesbian Mardi Gras parade, in Sydney, Saturday, March 5, 2016. Source: AAP
But Labor said if the senator was so confident that a plebiscite would take place and be approved by the parliament by the end of the year, what was the need for a plebiscite at all?
"I'm astounded the prime minister is refusing to let the parliament do its job," Mr Shorten said.
Mr Turnbull intended to waste $160 million of taxpayers' money on a plebiscite that would provide a platform for "destructive, bigoted views to be heard", Labor believes.
Labor has committed to legislate for marriage equality within 100 days of being elected.
Australian Marriage Equality national director Rodney Croome said if the government allowed a free vote in parliament there would be marriage equality next week rather than delaying until the end of the year.
"If there is to be a plebiscite the result should automatically change the law and not return to parliament for further debate and delays," Mr Croome said in statement.
Australian Christian Lobby managing director Lyle Shelton urged Australians to inform themselves of the far-reaching consequences of changing the definition of marriage in law.
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"If Australians value the rights of children to wherever possible have their mum and dad, if they value freedom of speech and parents rights to protect their kids from contested gender theory at school, they will vote `no' in the privacy of the ballot box," Mr Shelton said in a statement.
Mr Turnbull became the first prime minister to attend the Gay and Lesbian Mardi Gras on Saturday night, something Senator Brandis described as "completely unremarkable" given it is held in his inner-Sydney electorate of Wentworth and he has been several times before.
Greens Leader Richard Di Natale said it was a "great thing" that Mr Turnbull attended but he needs to back that with a vote in parliament rather than a plebiscite.
"He's got an opportunity to bring the parliament with him, a vote on marriage equality. We should have that done before the next election," Senator Di Natale told ABC TV.
