Environmentalism and sustainability need not fall on the political left or right, and there's space for a more centrist party, former Green MP Kennedy Graham says.
A new centrist green party is being talked about by a former Green Party leadership contender, Vernon Tava, who says he has been approached to start one up.
Dr Graham says he's not part of any discussions to form a new party but he does think there is room for one that is not wedded to the political left.
"Sustainability can be pursued both from the left and from the right as long as it is genuinely committed to environmentalism. You don't have to be left or far left as the only solution to sustainability," Dr Graham said.
He said politicians working to improve the environment should come from both sides.
"There are three philosophies in politics in the New Zealand Parliament: there's freedom, there's equality, and there's now sustainability - and sustainability has to be seen as separate and unique to itself.
He rejected the suggestion the new party would be 'blue-green'.
"It's neither red green nor blue green but ... would work with the left or right, it would be a quintessentially centrist party."
He said to have sustainability built into the Parliament in the long term, an environmentally focused party would - unlike the Green Party - need to work with both sides.
"It can work, obviously, with the left and right - and should, and will have to."
"If you listen to Vernon Tava - and I support this - you have government and you have opposition and if a political party says it's only going to work with one side of that house, then you're not going to get a long-term binding genuine consensus.
"That is required in any country - including New Zealand - for effective long-term or even medium term sustainability: You need environmental philosophy to be placed in the centre and to be working with both left and right."
However, he said the coalition government was making progress under its current structure.
"You've got extremely capable cabinet ministers in the form of, especially, James Shaw and Eugenie Sage.
He also rejected joining such a party, should it come to pass.
"I've met on a couple of occasions with Vernon, he remains a friend and a colleague but ... I haven't discussed it with him.
"For that matter I meet with James Shaw from time to time too.
"My active political career is over, I'm just interested in the theory and philosophy of sustainability."
He said Mr Tava had good leadership qualities.
"I was quite happy back in 2015 when both he and James ran for leadership of the Green Party because they both have the leadership qualities ... obviously he would not be the only person leading such a party.