A public rift is emerging in senior ranks of the Australian Greens with one senator declaring the party should look to the policies of US presidential candidate Bernie Sanders to boost support.

NSW senator Lee Rhiannon says the party is at a crossroads with Labor moving to the left on some issues and other minor parties pulling votes.

"The Bernie Sanders experience in the US shows that people with radical and anti-establishment policies can win mass support," she told Fairfax Media on Friday.

"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."

Federal Greens leader Richard Di Natale has made plain his ambition to steer the party towards the centre and broaden its electoral appeal.

But Senator Rhiannon wants the Greens to position themselves as a radical, anti-establishment force.

"I think we already are when you look at the policies but I would like more people to see us that way - that's what I think is urgently needed," she later told ABC Radio.

"The experience overseas is very exciting, it's inspiring people. There's big changes in our society. The Greens need to be part of that and ready to respond with policies that will deliver on what people want."

Former federal Greens leader Bob Brown labelled Senator Rhiannon a "Greens version of Tony Abbott" - a criticism she described as "extremely strong" and unpleasant.

Another unnamed Green MP expressed concern the party's media profile has fallen under current leader Senator Di Natale, saying the party was "pretty invisible at the moment".

Senator Rhiannon later backed away from her criticism of saying she shared responsibility for the party's plight.

"We have great policies ... it's how do we ensure people hear out message," she said.

"I acknowledge people hearing our message and being inspired by it is tough, and that's what I mean when I say we face a crossroads."