Left wing delegates to Labor's national conference are increasingly confident that a motion binding members to vote in favour of same-sex marriage will be passed later today.

Louise Pratt, from the party's Left, is expected to move an amendment to the ALP platform to force MPs and Senators to support gay marriage after the next election.

It is understood the motion will be seconded by Pat O'Neill from the right wing National Union of Workers.

One source from the Left, after attending a lunchtime caucus meeting, told the ABC "I am positive we'll get enough votes from elsewhere on the conference floor to pass this."

The view from the Right is increasingly pessimistic, with one delegate telling the ABC "we are having some real trouble on same-sex marriage".

At the moment Labor MPs have a conscience vote but there is a move from some in the Left faction, including Deputy Leader Tanya Plibersek, to ensure they would be "bound" to vote for marriage equality after the next election.

That would leave those MPs and senators who oppose gay marriage having to abstain or cross the floor, which could see them expelled from the party.

Opening the final day of the national conference today, Mr Shorten said Labor supported same-sex marriage and wanted it to be legalised in this term of Parliament.

"Let us ask of Mr Abbott that he gives a free vote to all members of his party and of course if we ask for him to give a free vote, we must extend that ourselves," he said.

Labor frontbencher, and member of the Left Anthony Albanese told Insiders that he strongly supports gay marriage but believes the party should retain a conscience vote.

"I'm of the view that you can have that strong position but be respectful towards people who, because of their faith, have a different point of view," he said.

"You can't call for tolerance and respect for diversity in my view whilst being intolerant."

Labor is also expected to change some of its rules today to give party members more say in the way it is run.

Mr Shorten called for the party to give its rank-and-file members more power.

But the details of how the so-called democratisation would work are still being figured out, with both issues expected to be discussed during the rules debate this afternoon.

The key issue of the conference was finalised yesterday when delegates accepted Mr Shorten's push for a future Labor government to have the option of turning back boats.