Labor Party powerbrokers have continued to ramp up their attacks on the Greens, with the Australian Workers Union labelling them as an extremist group that cannot be trusted.

The AWU's national secretary Paul Howes says the party is having a huge impact on national politics, despite remaining stable in the polls for years.

Labor's NSW Secretary Sam Dastyari told The Weekend Australian he will move a motion at next weekend's state conference to distance the party from the Greens and review preference arrangements.

His comments come after Victorian Labor on Friday decided to preference Family First ahead of the Greens in a state by-election for the seat of Melbourne.

Mr Howes says other states should follow suit, saying the Greens are the most dangerous fringe group in Australian politics.

He says the direction of the Greens is not consistent with the philosophy of the ALP.

"Now that the extremist wing of the Greens are in power, now that Bob Brown has been tossed out, it's incumbent on mainstream moderate Australian parties to expose the extremist nature of these parties, and the real threat they pose to the rights and job security of working people in this country," he said.

"The Greens do not represent mainstream Labor views, they do not act in the interests of mainstream Labor voters, and I view the Greens as an extremist party, not unlike a left-wing version of Pauline Hanson's One Nation. It is appropriate for Labor, the organisational party, to review our interactions with that party."

Mr Dastyari says Labor must stop treating the Greens like family and place them last in preferencing in seats where it is in the ALP's best interests to do so.

He says The Greens' inability to compromise is behind the push to preference them last at the next Federal poll.

"I think some of their individual policies agenda and some of the policies they vote are a bit loopy, are a bit to the extreme," he said.

"Secondly, and this is the real issue I have, is this attitude and this view they have on politics of 'all or nothing.'

"All mainstream political parties that want to participate in Australian political debate have to be prepared to compromise and I think the behaviour of The Greens when it came to the refugee debate was appalling, a refusal to budge on anything."

But Greens leader Christine Milne says her party does compromise and Mr Dastyari will only harm his own party by continuing with his campaign against The Greens.

"He's prepared to play so many political games as would see preferences go to the Coalition or Family First," Senator Milne said.

"That could not only put Tony Abbott in the lower house but it could give him control of the Senate."

'They've lost their way'

Greens Senator Sarah Hanson-Young has told Sky News that Labor is not in a position to criticise other parties.

"I think Labor voters are dismayed that the Labor Party just doesn't stand for anything anymore," she said.

"It's pretty clear, they are different to The Greens, they've lost their way, they've lost their principles and who knows what their values are rather than internal bickering."

Senator Milne yesterday responded to Mr Dastyari's accusations of extremism in her party by accusing Labor of aligning themselves with the real extremists by preferencing Family First ahead of the Greens.

Senator Milne said Mr Dastyari's comments were in fact an "attack on the Labor base"

"That's where the extremism is in Australian politics and the Greens actually represent mainstream values and mainstream opinion," she said.

"Labor Party people across the country will be horrified to think that if they vote for Labor they don't know if they will be electing a Coalition person or a Family First person.

"What it shows is the faceless men in the Labor Party do not have any principle any more, or any idea of what Labor stands for other than winning office.

"I think this attack from Sam Dastyari is actually an attack on the Labor base."

But Assistant Treasurer David Bradbury says the Greens hold very different values to the Labor Party.

Mr Bradbury says preferences are a matter for the state organisation - but the parties are not the same.

"I didn't receive any preferences from the Greens at the last election, and I'm certainly not out there canvassing or expecting anything from them in the future," he said.

"We will stand on Australian Labor Party values. That's what we're about and that's what we're delivering in Government."