National and Labour will be made to sweat over the weekend with New Zealand First putting off a decision on who to support until at least Monday.

Bill English will stay in Wellington over the weekend, while Jacinda Ardern is heading home to Auckland.

After a week of marathon negotiation talks with each party, Winston Peters has confirmed his party board will fly in to Wellington for a meeting with MPs on Monday.

A decision would be made at that meeting and announced as soon as possible, Peters told media at Parliament. Board members had booked to stay Monday night if the meeting stretches on.

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However, Peters - who wore a tie with the acronym TGIF (thank God it's Friday) - indicated getting an agreement shouldn't take too long.

New Zealand First leader Winston Peters with some members of his negotiating team. Photo / Mark Mitchell
New Zealand First leader Winston Peters with some members of his negotiating team. Photo / Mark Mitchell

"We know time's of the essence ... if we've done enough work, the consideration that happens on Monday should take far less than the time we're doing [with the work] we're involved with now," said Peters, who attended a caucus meeting that wrapped at 5pm yesterday.

"That includes doing the fiscals as far as we can go and making sure that we will have a very clear idea of what we need to enquire of the other parties to make sure there is no doubt as to the sum of our discussions."

It is likely public departments such as Treasury are now involved in checking costings used in negotiations, a process that is allowed under the Cabinet Manual.

National Party leader Bill English will be in Wellington over the weekend. A spokeswoman said, "our offices will be in contact as necessary".

Labour leader Jacinda Ardern arrived at Parliament yesterday, saying only that Labour has a process it will follow, but not elaborating further.

Labour needs the support of NZ First and the Green Party to form a Government, but is negotiating separate agreements with each party. It had wanted the Greens formally on board before Peters and his team make their final decision, so they can guarantee they have the numbers.

The Greens have been on standby to conduct a special general meeting of delegates via teleconference to get the at least 75 per cent agreement needed to sign off the agreement.

Greens leader James Shaw told reporters yesterday that negotiations with Labour were being finalised.

"We're pretty much ready to go. We're waiting for negotiations to conclude. There's still bits and pieces that we need to tidy up. We've got through the bulk of it ... we're nearing the end stages and at this point, I don't foresee any great trouble."

Shaw said that the Greens prefer a coalition deal to a confidence and supply arrangement, but "we've just gotta see how things go".

"Life is fraught with risk, and pretty much any scenario contains risks for the life of the [Green] party.

"It's not all about the future of our party. It's actually about the future of our country and what model of Government is best going to deliver on that."

Prior to the election, Peters said if he was kingmaker he would announce a decision by Writ Day - October 12 - but he defended taking longer, saying 10 days was not too long to wait.

Possible options include a full coalition inside Cabinet, a support agreement offering confidence and supply in return for some ministerial posts outside Cabinet, to sitting on the cross benches offering support on a case-by-case basis.