Hanson-Young may support plebiscite

Greens senator Sarah Hanson-Young says doing nothing on legalising same-sex marriage is not an option for her.

Senator Sarah Hanson-Young says she may split from the Greens and support a gay marriage plebiscite. (AAP)

Sarah Hanson-Young has flagged she might split from the Greens and support a plebiscite if attempts to legislate same-sex marriage fail.

"Nothing isn't an option for me," the senator told Sky News on Thursday amid concerns the issue could be off parliament's agenda for three years if a government plan for a plebiscite is rejected by the upper house.

Senator Hanson-Young said she would prefer the parliament exhaust all legislative avenues before considering a plebiscite.