National isn't ruling out doing an Epsom-style seat deal with any potential 'blue-green' party that arises between now and the next election.
Former Green Party member and failed leadership contender Vernon Tava says there has been a lot of talk about setting up an environmental party that could partner with National.
The Greens have never backed National, the latter of which lost the last election despite being the biggest party because it had no viable coalition partners.
National leader Simon Bridges told The AM Show he heard a bit of chatter over summer about it, but hasn't been involved.
"I haven't been in any talks, I haven't seen anything concrete. But I suppose what I'd say is the idea of it, look, it could be a valuable contribution. Because I think in truth what you've got in the Green Party that's in Parliament is a party that's very much to the left of Labour - so that's not for everyone.
"I think the idea of a party in the middle that wasn't about all the left-wing stuff, if you like, but was about the environment and doing something with that, could be quite powerful."
Mr Bridges says the Greens, who aren't technically in the governing coalition but support it on matters of confidence and supply, are more interested in drugs and "some of the trendy stuff that Golriz [Ghahraman, Green MP, ex-refugee and human rights lawyer] goes on about".
"A real centrist environmental party could be quite powerful."
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James Shaw, who defeated Mr Tava on the way to becoming Green Party co-leader, doubts a 'blue-green' party would make it to Parliament.
"What they are saying is they want to be a party that works alongside the National Party," he told Newstalk ZB on Sunday. "People who vote for the Green Party have shown time and time again that their vast preference is for us to support Labour-led Governments."
Mr Bridges, mindful of the need for a coalition partner with the demise of United Future and the Māori Party's inability to get a seat in 2017, said he wouldn't rule out helping a 'blue-green' candidate get a seat, in the hope they bring in more MPs - like National has done with ACT in the past.
"My job fundamentally is to get out and make sure National is the strongest party... I think we do need partners. But I think what you are going to see this year is whether it's this green idea, whether it's an indigenous Māori party, whether it's something else, I think you will organically see parties coming up to fill I suppose what is a void in the centre."