The Australian Greens are claiming credit for a push inside Labor to force its MPs to vote for same-sex marriage.

Deputy leader Adam Bandt believes his party and people who vote for the Greens pressured deputy opposition leader Tanya Plibersek into calling for a binding vote on her federal Labor colleagues.

The electoral threat from the Greens, especially in inner-city Labor-held seats, was forcing issues like gay marriage and climate change to "bubble up" higher on the agenda, he said.

"It's clearly having an impact," Mr Bandt told Sky News on Friday.

Ms Plibersek's push to scrap a conscience vote has split Labor MPs and senators, despite the party's platform being supportive of same-sex marriage.

She has called on party members to impose a binding vote on MPs at the ALP national conference in July.

Some inside Labor believe the Plibersek move is an attempt to prevent inner-city seats like her's falling to the Greens.

Opposition Leader Bill Shorten is not backing his deputy saying people should be convinced, not forced, on the issue.

Nor is she getting support from Anthony Albanese, who holds the inner-Sydney seat of Grayndler for Labor and is a strong campaigner for same-sex marriage.

"A conscience vote is seen, I think, as being the best way of getting it through parliament," he told the Nine Network on Friday.