Labour leader Jacinda Ardern says the Green Party will hold off ratifying any agreement to support a Labour-led government until after New Zealand First makes its choice.
Labour and National are both still waiting as the New Zealand First board and MPs resume their deliberations today over who to form a government with.
Ms Ardern told Morning Report all discussions with the Green Party have been settled, and the two parties were "pretty much ready to go".
But the Greens understood that their process of party members voting on an agreement needed to wait, she said.
"The Greens are aware that we're still in negotiations and talks and so having that other agreement made public while we're still in that position is something that could potentially compromise our conversation [with New Zealand First]."
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Ms Ardern said policy was driving discussions with New Zealand First and ministerial positions had not been talked about.
"People should take some heart by the fact they have been dominated by the nature of the government that will be formed rather than just simply around ideas of position."
The stability and durability of the next government would depend on whether they had enough in common to last the distance, she said.
On the discussions with New Zealand First, Ms Ardern said confidentiality was being respected and a considered process was necessary.
"Labour has engaged separately with the Green Party and separately with New Zealand First. A blind negotiation is the way that all negotiations have been conducted for past governments.
"Of course, we have to be mindful that in the coalition or agreements that we sign that they are compatible with one another."
Eventually there would have to be a discussion around the nature of the government, she said.
"Discussions have been dominated by areas of consensus, agreement, disagreement on the issues that matter and it hasn't been a discussional negotiation that's been dominated by what particular roles individuals will play.
"We have been entirely focused on policy," she said.
"The Governor-General of course cannot confirm that a government's been able to be successfully formed unless she can see that there is the confidence of the House behind that agreement.
"So that means knowing that there's either confidence and supply or a coalition agreement or some iteration that demonstrates that the votes are there for a government to be formed."
New Zealand First's internal talks to decide which major party it will support to lead the next government will continue into their second day today.
New Zealand First's board and caucus were locked in a closed-door meeting all day yesterday, weighing up proposals from both major parties.
The meeting wrapped up at Parliament about 6pm last night and the party said it would not be making any announcements.
Discussions were expected to continue at Parliament from 9am this morning.