The factional fight within the Greens is escalating into an all-out public brawl, with a senior member of Richard Di Natale's team now openly questioning the party's direction and prospects under his leadership.
NSW senator Lee Rhiannon has told Fairfax Media the party is at a "crossroads" and should channel the radical worker-driven policies of US presidential candidate Bernie Sanders to re-energise supporters - but her comments have drawn fire from party elder Bob Brown, who has re-entered the political fray to label her a wrecker and the "Greens version of Tony Abbott".
Other Greens figures say they are worried the party is losing votes to Labor and other minor parties under Senator Di Natale, as he attempts to steer it away from its protest roots and into the mainstream. There are concerns too from Greens in and outside Parliament the party has become "invisible" under Senator Di Natale's less media-driven approach.
But Senator Di Natale's supporters say the mostly NSW-based dissenters are just bitter about losing power and influence.
The public fight comes after the formation last month of a new far-left, anti-capitalist faction within the NSW Greens called Left Renewal. Senator Rhiannon says she is not a part of the faction, but she is closely linked to a number of its members and has publicly defended its right to exist.
"The Greens are at a crossroads, with Labor appearing to move left on some issues and minor parties also pulling our votes away," Senator Rhiannon told Fairfax Media this week.
"We need to be able to inspire people and demonstrate that the Greens can challenge ruling elites and end the obscene and growing inequality both at home and abroad.
"The Bernie Sanders experience in the US shows that people with radical and anti-establishment policies can win mass support. How the Greens inspire people to join with us and vote for us is our challenge in 2017."
New polling analysis - commissioned by Senator Di Natale's critics and obtained by Fairfax Media - suggests the party's vote has been sliding since the July 2 election.
Based on data from every published opinion poll in 2016, the analysis finds the mean first-preference support for the party in the first half of the year was 11.23 per cent, compared to 10 per cent by the end of it.
"Many are waiting to see if Di Natale has the ability to put the spark and courage back into the Greens," a source connected to the polling said.
Another senior Green, who did not want to be named but is not part of the NSW factionalism, agreed the party's media profile had diminished under Senator Di Natale - partly because of the crossbench had taken the focus in the Senate but also because of a "culture" at the top.
"We're pretty invisible at the moment," the source said.
However, those aligned with Senator Di Natale say any decline in national polling numbers can largely be blamed on the "radical agenda" of the NSW branch dragging them down.
Dr Brown, who led the party from 1996 to 2012, believes the NSW branch is holding the party back, saying Senator Rhiannon and "her Left Renewal" are determined to destabilise the party.
"People say two things to me: what a good fellow Richard is and when is Lee going. NSW voters have often told me they won't vote Green until Lee goes. That's why Labor loves her," Dr Brown said.
"When it comes to political white-anting, Lee is the Greens' version of Tony Abbott."
One of Senator Di Natale's deputies, Scott Ludlam, urged an end to the divisions, saying progressives must unite to "overcome the hate and fear being peddled by people like Pauline Hanson and Donald Trump".
"Let's stop wasting energy squabbling and continue to work to advocate serious alternatives to unfettered, crony capitalism. That's what Richard and our Greens team are doing."
The party's performance at the election was a mixed bag. While there was a small swing towards them in the lower house they failed to pick up any new seats.
Their vote in the Senate was similar to 2013 - 8.65 per cent nationally - but they lost one senator from South Australia. They failed to replicate their 2010 success - when they garnered 13.1 per cent of the Senate vote - despite the public's palpable anger with the major parties.
NSW was among the worst-performing states. In an official, internal post-election analysis obtained by Fairfax Media, the Greens acknowledge the NSW result was disappointing. It concludes that with equivalent resources in NSW and Victoria, "there must be other reasons why the party continues to go backwards in NSW".
Fairfax Media has also obtained Greens membership data that shows there has been a small but steady increase in member numbers in most states since Senator Di Natale took over. However, the number of members in NSW has declined from 4689 in July 2015 to 4098 today, leaving overall national numbers stagnant.
And a membership survey conducted in November of last year suggests 85 per cent of Greens members want the party to be a party of government, rather than one of protest - a figure seen as a strong endorsement of Senator Di Natale's more mainstream approach.
About a quarter of members nominated NSW tensions - unprompted - as a key challenge holding the party back.
Left Renewal is seen as an escalation in the long-running factional battle between the heavily socialist so-called "eastern bloc" of the Greens and the middle-class environmentalists they dismiss as "tree Tories". Senator Di Natale has described the group's anti-capitalist agenda as "ridiculous" and has called on its members to consider joining another party.