Two bills to allow gay marriages in Australia were introduced in Parliament on Monday but may fail because of political conflicts.
The bills are essentially the same, lifting a current ban on same-sex marriages while letting religious ministers refuse to solemnize ceremonies inconsistent with their beliefs.
A lawmaker from the Greens party, a coalition partner in the minority government, introduced the first bill, and the second was introduced by a Labor lawmaker weeks after the ruling party lifted its opposition to same-sex unions.
The Greens party has long called for legal recognition of gay marriage in Australia, while the major political parties have opposed it.
In introducing his party's legislation, Greens lawmaker Adam Bandt told Parliament he was disappointed that Labor lawmakers had refused to cooperate on gay marriage.
"We know that as things stand, if either of these bills is put to a vote now, we know it will fail," Bandt said.
The Greens say gay marriage supporters need to be unified to attract a majority.
Labor lawmaker Stephen Jones said his bill was more likely to win over his party's lawmakers as well as the opposition. Many conservatives are particularly hostile toward Greens, whom they regard as too radical.
Jones said his bill "follows an international trend to end discrimination when it comes to marriage," noting that around 10 countries and several U.S. states allow same-sex marriage.
He also said gay marriage law reform is a human rights issue, and that it is supported by most Australians.
Though Jones belongs to Labor, the support of fellow Labor lawmakers is not guaranteed.
The party reversed its long-standing opposition to gay marriage in December, but crucially, Prime Minister Julia Gillard decided to allow members to make a rare "conscience vote." That means they can vote by their personal beliefs without risking expulsion if they defy the party line.
Gillard herself opposes gay marriage, and the Liberal Party-led opposition coalition remains opposed to gay marriage.
Australian law was amended in 2004 to make clear that only a union between a man and a woman can be legally recognized as a marriage. No timetable has been set for a vote on either bill that would lift that ban.
Liberal lawmaker Alex Hawke, a gay marriage opponent, said Monday that the issue is not about human rights, since same-sex couples face little if any discrimination under federal law.
"We're talking about a radical proposal to undermine a fundamental social institution that has been the basis of our society for thousands of years," Hawke told Parliament.