KEVIN Rudd made a major commitment to gay marriage during his showdown debate with Tony Abbott last night.

Mr Rudd pushed a promise for a free vote as this year's election sees candidates supporting it more than ever before.

During the first debate of the federal election the Prime Minister promised that if re-elected, within the first 100 days the Labor government will introduce a bill to legalise same-sex marriage - as revealed they would do by news.com.au on Sunday.

"I support marriage equality, I believe this is a mark of decency to same sex couples across the country and for that to be formalised," Mr Rudd said.

"We will allow a full conscience vote, I would appeal to Mr Abbott to do the same."

The Prime Minister struck a clear line between his support for same sex marriage laws and the Opposition Leader's strong personal condemnation of them.

Legislation for marriage equality within 100 days of the election with full conscience vote. I believe this is the right thing to do. KRudd — Kevin Rudd (@KRuddMP) August 11, 2013

Labor wants to pressure Mr Abbott on a commitment to a conscience vote in the issue, win or lose this election.

Mr Abbott was more coy in his response, saying his priority is reducing "cost of living pressure".

"It's a very important issue, I know how important an issue it is, but it's not the only important issue," he said.

The Greens already have urged a multiple-party agreement on gay marriage.

National Director Australian Marriage Equality convener Rodney Croome, said, "Mr Rudd's plan for prioritising marriage equality in the first 100 days of a Labor Government is an important step forward, but he can't achieve this reform himself, putting the onus back on Tony Abbott to allow a conscience vote."

"Our hope that Tony Abbott will allow a conscience vote has been strengthened by his declaration during the debate that marriage equality is 'a very important issue' and the fact he pointedly didn't defend the status quo or argue against the reform."

"This evening's debate shows how far Australia has come since 2010 when both leaders openly defended the exclusion of same-sex couples from marriage."

"For both current leaders it is not so much a matter of if, as when."

While Rudd's support on the issue has earned him a few extra votes, no one party can deliver reform and he we will need to follow in the footsteps of Prime Minister's David Cameron (UK) and John Key (NZ) by reaching across the aisle and collaborating with all sides of the political spectrum.

In the last couple of years five marriage equality bills have been introduced to Parliament but all have failed to pass.

#itstime all sides of politics work together to achieve #marriageequality #vote4love — AU Marriage Equality (@AMEQUALITY) August 11, 2013

For legislation to be passed, Australian Marriage Equality believes the formation of a national cross party group is the key to move the issue forward.

The group would be similar to one in operation in NSW which includes The National's Trevor Khan, Liberal's Bruce Notley-Smith, the Greens' Mehreen Faruqi, Labor's Penny Sharpe, and Sydney Independent Alex Greenwich.

"Because marriage equality will be achieved by a conscience vote and not by any one party or leader, we want Mr Rudd and Mr Abbott to approach it in a way that's co-operative rather than confrontational," Croome told news.com.au.

"Marriage equality has been achieved in Britain and New Zealand by political leaders reaching across the political divide and working together, not by them striking a pose of scoring political points."

Marriage equality could be delivered as soon as the next parliament sits, but it will require co-operation between all parties.

"Whoever wins the election, the way forward on marriage equality is for politicians of goodwill in all three parties to work together, in the same way they are already successfully doing in NSW."

Three trailblazers from the major parties have expressed interest in the formation; openly gay Liberal candidate Kevin Ekendahl, Federal Labor MP Graham Perrett and Greens Senator Sarah Hanson-Young.

"The nation is more than ready for marriage equality but the way is blocked by a political log-jam of the old parties' making," said Hanson-Young.

"I'm as keen as ever to collaborate with MPs from any side of politics to get this popular reform through the federal parliament so that all Australians can marry the person they love."

The Greens called for a new marriage equality bill today - jointly sponsored by Labor, the Liberals and the Greens - to be introduced to the new Parliament by November and voted on by Valentine's Day 2014.

Best way to achieve #MarriageEquality is cross-party support in the Parliament. A bill co-signed by Greens, Labor & Liberal. I'm up for it! — Sarah Hanson-Young (@sarahinthesen8) August 11, 2013

A spokesman for Tony Abbott did not release a statement to news.com.au by time of publishing but Liberal candidate Kevin Ekendahl told news.com.au if elected he would be "unequivocally and unashamedly supporting marriage equality and fighting vigorously for a conscience vote within the Liberal party.

"I've always held the same point of view that I think two people regardless of sexuality should have the same laws, being an openly gay candidate I'm never going to support legislation that contributes to my own discrimination."

Kevin Rudd earlier this year declared he had bowed to the arguments of family and from a gay friend and now backed the marriage equality campaign, thus putting him at odds with then Prime Minister Julia Gillard as well as Mr Abbott.

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