Greens leadership candidates are jostling for position following the shock resignation of Larissa Waters.
The Queensland senator announced late on Tuesday she had quit as leader of the Greens due to worsening kidney disease, saying her condition - which was not publicly known - had deteriorated.
Members of the minor party are expected to choose a new leader during a regularly scheduled two-day policy meeting in Sydney starting on Wednesday.
South Australian senator Sarah Hanson-Young has confirmed she will seek the party leadership in a social media post.
AAP has been told senators David Shoebridge and Steph Hodgins-May might also be seeking a joint ticket.
Senator Shoebridge would not be drawn on the speculation at a press conference on Tuesday morning.
"I'm not here to rule anything in or anything out in terms of leadership. That will be a matter that the party room makes a decision on," he said.
Deputy leader Mehreen Faruqi and Tasmanian senator Nick McKim are also understood to be running for a leadership position.
Former Greens senator Andrew Bartlett said the intense focus on the leadership missed the point, and the party's success was not tied to an individual.
"It's not all about who is the fricking leader. It's about your messaging," he told AAP.
"David Shoebridge has had immense cut-through with a bunch of issues. Barbara Pocock has, Jordon Steele-John has. (It) doesn't mean they need to be leader to do that ... it's about the team."
However the internal vote lands, there is a strong sense of optimism among former party leaders for whoever takes the reins in coming days.
"(The Greens are) currently sitting on 14 per cent on the averaging of polls, which is unprecedented, and Larissa can be very proud of that," inaugural Greens leader Bob Brown said.
Dr Brown would not put his support behind any one contender but said there are "three or four options" with the experience and ability to take on the major parties.
"The future is looking very bright."
Former Greens leader Adam Bandt said voters are looking for action.
"There is a growing sense, especially amongst younger people now, that the government is just not doing enough," the Australian Conservation Foundation chief said.
The Greens suffered the loss of three lower house seats, including Mr Bandt's long-held seat of Melbourne, at the 2025 election due to a swing away from the party among inner city voters.
South Australian Greens senator Barbara Pocock said she was deeply saddened by Senator Waters' decision to step back.
"Larissa is one of the good people. Working with her has been a joy and will be again. Rest up and get well beloved comrade. Much love," she said in a post to social media.
Prime Minister Anthony Albanese wished Senator Waters well and thanked her for constructive engagement during her tenure.
"I obviously have differences with the Greens political party, but this is a human issue. I can also have compassion and I have a good relationship with Larissa," Mr Albanese told reporters.
