Australia has plans to hold a voluntary popular vote by post on legalising same-sex marriage.
The non-binding vote is facing resistance from opponents who say it is a waste of money and could lead to hate crimes in gay communities.
“I know what a hard debate is like. But I tell you, have a read of some of the things which are said about us and our families and then come back here and tell us this is a unifying moment,” said Penny Wong, an opposition Labor senator.
Recent polls have shown support for changing the law. A poll released last week showed 67 percent of women and 59 percent of men want to see same-sex marriage legalised.
The Australian government said ballots could be sent out by 12 September. The responses would be due by 7 November, and the result would be released on 25 November.
Australia is one of the last developed nations in the English speaking world that still have not legalised gay marriage.
Political analysts have said that marriage equality issue could cause Mr Turnbull serious difficulties if it is not finalised before the election due in 2019.
Peter Chen, a politics lecturer at University of Sydney said: “Turnbull would get a win if the same-sex marriage issue could be legislated before Christmas,”
Former prime minister and a rival of Mr Turnbull, Tony Abbott, said he would take a lead role in the campaign against legalising gay marriage.
“If you don’t like same-sex marriage, vote no. If you’re worried 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,” he said.