澳大利亚选民开始收到同性婚姻的民调选票

Tuesday marks the start of a month-long voluntary vote that could eventually legalize same-sex marriage in Australia.

As many as 16 million Australians will receive a mail-in ballot asking them to vote either "yes" or "no" on the issue and mail it back by November. If a majority of ballots are marked "yes," Parliament will follow through with a formal vote in December.

A new opinion survey released Tuesday indicated 70 percent of those questioned said they support same-sex marriage.

Prime Minister Malcolm Turnbull, who says he will mark "yes" on his ballot, launched the voluntary mail-in vote after lawmakers rejected a plan to hold a compulsory vote known as a plebiscite.

Gay rights advocates unsuccessfully challenged the plan in Australia's High Court, arguing that Turnbull's government does not have the authority to spend $97 million on the mail-in ballot.

Advocates also expressed fears the vote could expose Australia's gay, lesbian and transgender community to harm. They are demanding lawmakers hold a simple up-or-down vote.