THE Foreign Affairs Minister, Bob Carr, has become the latest Labor politician to declare his support for same-sex marriage.
Senator Carr, who has not made his position on the issue public until now, said yesterday that his support for gay marriage was consistent with his work as NSW premier to remove from state laws discrimination against gay and lesbian people.
While he respected the views of those who held more conservative opinions on marriage, it ''seemed churlish to deny access to marriage to groups that wanted it'', he said.
The Senate is about to begin debating proposals by four Labor senators to legalise gay marriage. While support for same-sex marriage is stronger in the Senate than in the House of Representatives, campaigners are pessimistic about the bill passing when it goes to a vote this week.
Nine Greens senators and at least 20 Labor senators are expected to vote for change, but a further nine votes will be needed for the bill to pass. Among those yet to declare their position are the Communications Minister, Stephen Conroy, and the independent senator Nick Xenophon.
Coalition senators are bound to vote against change. While the Coalition does not expel members for voting against its position, campaigners say Coalition senators who support same-sex marriage are being strongly discouraged by the leadership from voting against its position.
The Australian Marriage Equality convener, Alex Greenwich, said that if the bill was defeated it would not be the last vote on the issue.
Momentum for change was ''unstoppable'' and ''huge progress'' had been made since 2009, when only six senators, all from the Greens, voted for a bill to legalise same-sex marriage, Mr Greenwich said. ''Now we are able to see how far we've got with this campaign and how much more we need to do,'' he said.
Mr Greenwich said that before next year's election, campaigners would target Liberals in inner-city seats, such as Malcolm Turnbull, Josh Frydenberg and Kelly O'Dwyer, to put pressure on the Coalition to allow its members a free vote on the issue. He said same-sex marriage would be legalised ''state by state and territory by territory''.
Tasmania's lower house has already passed a bill to legalise same-sex marriage, while efforts to make the change are under way in South Australia and the ACT, and the Greens have announced they will introduce gay marriage legislation in the West Australian Parliament.
Mr Greenwich called on supporters of gay marriage to work together. There are no less than four separate bills to legalise gay marriage before federal Parliament, two sponsored by the Greens and two by Labor MPs.
''It's great that we have so many people within our Parliament wanting to champion this reform. But we need them to champion this together, because that's how this will happen,'' he said.
The Greens senator Sarah Hanson-Young, who has her own gay marriage bill before the Senate, accused Labor of a ''cynical ploy'' to push the issue off the agenda by putting it up for a vote before there was sufficient support for it to pass. She has invited other senators to co-sponsor her bill.
''To me it's about getting the legislation through … it shouldn't matter whose name is on the bill,'' she said. ''You've got to remember that in every other country where marriage equality has been achieved, it was never done on the first time.''
