Greens 'unlikely' to back Labour-NZ First from outside the tent

Few expect the Greens to sign a deal with National, but leader James Shaw says there are potential roadblocks to a Labour-Greens-NZ First Government too.

NZ First is the larger of the two parties, and hasn't nailed its colours to the mast like the Greens, who've openly backed Labour in their 'vote for change' campaign. It's arguable this puts NZ First in a stronger bargaining position when it comes to forming a coalition.

Asked if the Greens would back a Labour-NZ First Government on confidence and supply, Mr Shaw was blunt.

"The Green Party would be unlikely to sign up to that kind of deal," he told The AM Show on Monday. "We are in politics in order to make change."

Mr Shaw said change would be unlikely to happen if they sided with National, and the Prime Minister doesn't appear to be expecting a call either.

"Because of their clearly articulated public position ruling National out, they would have to indicate that position was changing and there has been no indication," Mr English told The AM Show.

Mr Shaw says the National Party would have to fundamentally change to get the Greens on board, but is taking a 'never say never' attitude.

"I can't predict the future. A lot of things would have to change with the way the National Party conducts the economy in order for us to be able to sign up to that.

"Fundamentally, the kinds of things we are trying to advance here around climate change, ending poverty, cleaning up our rivers, those are actually economic questions - and the consequences that we are seeing in the environment and in society are a function of the way that they manage the economy."

Mr Shaw makes no apologies for the Greens' pairing with Labour this time around though.

"It was fair to let voters know where they stood. The vast majority of voters want to know, 'Am I voting for the status quo or am I voting for change?'"

He believes the election result signals a vote for change, even if the Green vote slumped to 5.9 percent.

"It's pretty sad to lose a number of members of caucus, but also pretty excited about getting Chloe Swarbrick and Golriz Ghahraman in as well."