AustraliaPride_March2016
Participants take part in the annual Sydney Gay and Lesbian Mardi Gras Parade in Sydney, March 5, 2016. Getty Images/AFP/PETER PARKS

Australian Prime Minister Malcolm Turnbull backed away from a pledge by one of his senior ministers on Sunday that the government would hold a public vote on same-sex marriage later this year if it is reelected.

A spokeswoman for Turnbull said the government was committed to holding a plebiscite, or public vote, as soon as possible after the election but had not committed further to the timing.

Attorney-General George Brandis had earlier said the vote would occur before the end of the year and that the legislation would immediately be pushed through parliament if the public voted in favor of same-sex marriage.

"We will be going to the election promising a plebiscite before the end of the year," Brandis told Sky News.

The confusion adds to perceived instability in Turnbull's conservative Coalition government, just days after Deputy Prime Minister Barnaby Joyce called for government unity.

Turnbull, who became leader in a party room coup in late 2015, is under pressure on several policy fronts including tax and climate issues as his opinion poll ratings plummet ahead of the election and a critical budget.

Some of the party instability has been blamed on the man he toppled, former prime minister Tony Abbott, who remains powerful within the conservative faction of the government.

Australia has been criticized by international human rights groups over its slowness to act on same-sex marriage. Several countries, including Canada, the United Kingdom, United States, France, New Zealand, Ireland and South Africa, have already amended their marriage laws to recognize same-sex unions.

Turnbull, considered a moderate, had brushed off criticism from conservatives to become the first sitting prime minister to attend Sydney's annual gay Mardi Gras parade on Saturday.

"I'm very proud to be the first PM to attend," Turnbull tweeted, along with a photograph of himself and wife Lucy at the world-famous lesbian, gay, bisexual and transgender pride parade through Sydney's inner streets.

The federal opposition has put pressure on the government to move quicker on same-sex marriage, pledging to skip a plebiscite and introduce a bill to parliament within 100 days if it wins the federal election.

Turnbull's government remains ahead in the polls for the election, which the prime minister has indicated is likely to be held between September and November this year, although the gap has narrowed in recent weeks. Political wrangling has also left open the option of an election being held in July.