The move to force Labor MPs to vote for same-sex marriage could drive a wedge through the party.

The deputy leader Tanya Plibersek wants the ALP National Conference in July to decide that MPs should no longer be given a conscience vote on gay marriage.

Her move has triggered a backlash in the party, with some arguing she has set back the cause of marriage equality by up to 10 years.

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Ms Plibersek argues for a binding vote on marriage equality saying it is about ending discrimination. She said conscience votes should be limited to issues like abortion and euthanasia.

“Conscience votes in the Labor party are reserved for issues of life or death … I don’t think this is an issue in that category,” Ms Plibersek told the ABC’s Q&A program.

“I think this is an issue of legal discrimination against one group in our community. Do we have a conscience vote about whether we allow racism in our community?

“Do we have a conscience vote on whether we allow sexism or ageism, we don’t.”

The party narrowly voted at its last conference to let MPs to have a conscience vote on marriage equality, but this time the support for a binding vote instead appears to have grown, particularly with the left gaining numbers in Queensland.

But if the push succeeds, it could create a mess for the party with some considering whether they would abstain or more seriously, cross the floor, which would risk expulsion under party rules.

Labor frontbencher Gai Brodtmann supports same-sex marriage but does not think MPs should be forced to either vote for it or to break the rules.

“I support marriage equality but I also support a conscience vote. I like to think that we are a tolerant party that we can tolerate, accommodate a broad range of views. We’re a broad church,” Ms Brodtmann said.

Sources say some MPs with strong religious views would cross the floor and then either face expulsion — or resign from Labor sit as independents — causing a split.

‘We should have a uniform position on marriage equality’

Labor frontbencher Stephen Jones argued there is not a need for a conscience vote, but he points out churches would not be forced to conduct same-sex marriages.

“I don’t think removing discrimination should be an issue of conscience. I think any proposition that we vote on should carefully deal with the issue of religious freedom,” Mr Jones said.

“I don’t think churches should be forced to marry a couple against their precepts once that issue is dealt with. I think we should have a uniform position on marriage equality and I think it should be a position which is binding on all federal MPs.”

There is anger and bewilderment inside Labor that there is a renewed push for a binding vote on the issue when the ALP has been criticising the Prime Minister for refusing to give the Coalition a conscience vote.

Ms Plibersek said she does not accept Labor’s stand affects whether the Coalition agrees to give its MPs a free vote.

“It’s actually been Labor policy since 2011 since our national conference to have a conscience vote. There’s been no movement from the Liberal Party in that whole time to move away from their position which is Tony Abbott’s position which is no to marriage equality.”

– ABC