Australians will reportedly be asked to vote in February 2017 on whether they want same-sex marriage to be legalised.
Prime Minister Malcolm Turnbull is expected to inform members of the Liberal National Party (LNP) of the new timeline for the vote at a party meeting in September, officials said on Sunday.
A February plebiscite on the issue would break Turnbull's election promise that the Australian people would vote on the issue in 2016, Xinhua news agency reported.
A spokesperson for Turnbull said that a recommendation from the Australian Electoral Commission (AEC) warned against holding the vote in 2016.
"The government has always said that a decision on same-sex marriage will be made by a vote of all Australians in a national plebiscite to be held as soon as practicable," the spokesperson said on Sunday.
The plebiscite would be a non-binding vote which would ask voters "do you approve of a law to permit people of the same sex to marry?"
A bill to legalise same-sex marriage in Australia would then be introduced in parliament with MPs expected to vote yes or no depending on how their electorate voted on the plebiscite.
Conservative MPs from Turnbull's LNP have already said that they will be voting against the bill regardless of the result of the plebiscite, prompting same-sex marriage advocates to label the process as a waste of time and money.
Opposition leader Bill Shorten is expected to launch a last-minute bid to legalise same-sex marriage by introducing a bill to parliament in the coming weeks.