Coalition talks for a new government are entering their final stages but New Zealand First leader Winston Peters has delayed any decision beyond his self-imposed deadline of tomorrow.

He told reporters at Parliament last night he expected discussions with parties to be completed by tomorrow night.

But he could not say exactly when the decision would be made or announced.

"We have got a few logistical things to work out but as soon as possible after [Thursday night]," he said.

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"It depends on other parties as well. But I can't answer for them."

The deadline was set by Peters several months ago - to coincide with the return of the writ, which lists the name of every successful constituency candidate who are then considered to be members of Parliament - but there is no reason a decision needs to be made in a hurry.

Peters is giving nothing away about which way he might be leaning as the agreements between National and Labour take shape.

But he is mindful that there is going to be deep disappointment with whatever party is chosen.

"Whatever decision we make it will cause disappointment and anguish," he said after a marathon series of meetings yesterday.

Asked to elaborate, he said: "This [isn't the All Blacks, this is] politics, right, and before you even get on the paddock, there are a whole lot of people that don't want you to be there, some want you to be there and some want you to win, some want you to fail - that's politics."

Parties were still discussing policy yesterday - and had not yet started talking about the type of arrangement - full coalition, confidence and supply with ministers outside Cabinet or on the cross benches - but Peters has said that would be discussed last.

He and New Zealand First colleagues held four lengthy meetings with both parties and have four more planned for today.

Peters made it clear yesterday that despite the Greens' wish to be in full coalition, he wants nothing to do with the party.

He expects Labour to sew up a watertight commitment of supply and confidence from the Greens with no involvement at all from himself.

He suggested the reason for keeping the Greens out of contact was because the two parties had presented themselves as a bloc since June last year - although he took the same attitude to the Greens in 1996 and 2005 when there was no bloc.

"[For years] they all campaigned together, hugging [and] loving each other," Peters told reporters.

"They ran with an MOU [memorandum of understanding] for all those months, in fact years, and now you want me to explain this ... why don't you go and ask them yourself."

The deal between the Greens and Labour is likely to have been all but concluded and will be waiting for the green light by a special meeting - which may be convened digitally.

Ardern has said she would be treating the Green Party fairly in negotiations and reiterated that yesterday.

"We are going to be absolutely fair-minded in all our negotiations around the role that each party plays and what they bring to the table."