Sydney - Australia's opposition Labour party introduced a bill into parliament on Monday aimed at legalising same-sex marriage, stepping up pressure on Prime Minister Tony Abbott to allow a conscience vote on the issue.
Building on the momentum of Ireland's recent successful referendum, the legislation plans to replace the current definition of marriage as an act between "man and woman" with the words "two people".
"This parliament can change a law that no longer describes modern Australia and pass a law of which we can all be proud," Labour leader Bill Shorten said in tabling the proposal.
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"Let us delay no more. Let us embrace a definition of marriage that respects, values and includes every Australian."
Labour does not have the numbers to pass the bill and debate was adjourned. But it is using the draft legislation as a challenge to Abbott to allow government MPs a free vote on an issue believed to have broad community support.
Gay marriage opposition
Abbott's conservative government opposes gay marriage, and the Liberal party has previously refused to let members have a conscience vote.
A lower house vote on the issue in 2012 was defeated 98 to 42 after Abbott refused to allow his MPs, then in opposition, to break party lines.
The prime minister, who has a gay sister, last week promised a "full and frank" debate on gay marriage, but said on Monday it was not a priority.
"I accept that same-sex marriage is a significant issue. It's an important issue. It's important to many people," he said.
"But frankly, this government's absolute fundamental priority in the budget session of parliament is to get the most urgent budget measures through."
‘Let’s see where it goes’
Asked whether he felt momentum was building to change the law, Abbott, a staunch Catholic, said: "Let's see where the community debate goes.
"There's a range of views on both sides of the issue, and it's an issue upon which decent people can disagree, and let's see where it all goes."
Same-sex couples can have civil unions or register their relationships in most states across Australia, but the government does not consider them married under national law.
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Australia is seen as lagging behind a growing number of countries on marriage reform, and Shorten said Ireland's yes vote had stirred him into action.
"I thought - if the Irish can do it, why can't we?" he said.
"How can Ireland, New Zealand, 37 US states, England, Scotland, South Africa, Canada, Brazil, Iceland and Uruguay, how can they all be ahead of us?
"Twenty countries have already recognised the merit of marriage equality. I am confident Australia will."