UPDATED 6.29pm: There will be no announcement on a new government tonight.

New Zealand First is holding a meeting of its caucus and board to agree on supporting either National or Labour.

LISTEN ABOVE TO WINSTON PETERS TALK TO BARRY SOPER.

A spokeswoman says that meeting will continue tonight and reconvene tomorrow at 9am.

Leader Winston Peters has said an announcement will be made as soon as possible after the meeting ends.

One MP, Mark Patterson, arrived ahead of the meeting and said a lot of clarification had been needed over the weekend on the coalition negotiations held with the main parties last week.

He's not the only one signalling that it could take a little longer than Monday to make a decision.

National leader Bill English said his party was yet to talk to kingmaker Winston Peters about ministerial positions and the NZ First board would not have a completed agreement to sign off on.

"The discussion NZ First are having today is another step in the process, but it's by no means the final step in actually agreeing a government," Mr English said.

NZ First holds the balance of power and can either grant National a fourth term or make Jacinda Ardern prime minister in a Labour-led government.

If it goes to the centre-left, the Greens have to be part of the deal because NZ First and Labour don't have enough seats between them for a majority.

A Greens' spokesman said about 170 delegates were "ready to go" for a teleconference that would sign off their support of any agreement. It would need 75 per cent support.

NZ First could decide to form a full coalition government, with its MPs holding cabinet positions, or go for a looser support agreement with ministerial positions outside cabinet.

It may alternatively choose to stay on the cross benches and abstaining on confidence votes, which would allow National to continue governing because it has the most seats.

NZ First has nine MPs and its board has 14 members, including Mr Peters and his deputy Ron Mark.

Mr Peters insists he won't make the decision and says it will be entirely up to his caucus and board.

Ms Ardern and Mr English are bound by a confidentiality agreement until Mr Peters announces the decision.