Thousands have rallied in Sydney for a free vote when Labor's same-sex marriage bill is introduced to federal parliament on Monday.
Deputy Labor leader Tanya Plibersek told the cheering crowd it was time for change.
"This is the last piece of unfinished business," she said of gay and lesbian rights.
Ms Plibersek said a bipartisan approach to the bill would give it a much greater chance of succeeding, especially if someone in the coalition seconded it.
"This is a matter that transcends politics," she said on Sunday.
