The New Zealand First board and its MPs will resume their discussions tomorrow about whether to form a government with National or Labour.
The party has been meeting behind closed doors at Parliament since 10.30am today, weighing up policy concessions from the two major parties.
Just before 4.30pm, NZ First issued a statement which said the discussions were continuing and the meeting was expected to go on for several more hours.
The meeting wrapped for the night just after 6pm, with talks set to resume at 9am tomorrow.
The party said it would not be making any announcements tonight.
While face-to-face coalition talks with National and Labour wrapped up last week, negotiations are still ongoing regarding ministerial positions and governing arrangements.
NZ First leader Winston Peters made few comments on arrival at Wellington airport this morning, declining to say whether the board would make a final decision today.
He also refused to say whether the talks were more advanced with one side, but did confirm that ministerial positions had not yet been discussed with National.
National leader Bill English told Morning Report today that there were still unresolved issues and further talks were needed.
"While New Zealand First are having a discussion today, they won't be dealing with completed agreements because there's still outstanding issues."
The two parties had been in contact over the weekend to clarify stances on various policies, he said.
"We come to this negotiation with 56 seats in the Parliament, significantly the largest party.
"That's reflected in the weight of discussion about the policies so far, but there are still matters that need to be completed."
He expected an announcement by the end of the week, but was not "putting deadlines on it".
"I think the public are expecting the formation of a government pretty shortly."
No confirmation on Kermadec Marine Sanctuary
Arriving at Parliament this morning, NZ First MP Mark Patterson said the caucus had "a lot to get through".
Asked whether he hoped a decision would be made today, he said, "It's important we get it right, isn't it? That's the most important thing".
Fellow MP and former Labour minister Shane Jones said he was looking forward to meeting with the board.
He said today was a "very important day" on the Māori calendar.
The Māori Lunar Calendar names today as Tangaroa-a-kiokio: "a good day for taking eels, fishing and for setting crayfish and eel traps".
Mr Jones was also asked about reports that the proposed Kermadec Marine Sanctuary had been part of coalition negotiations between Labour and the Greens.
He said he was not aware of the matter and would leave any response to Mr Peters.
"But you know my background," he said. "I was the chairman of the Māori Fisheries Commission."
The Māori Fisheries Commission and some iwi had been planning legal action to stop the sanctuary and before the election the Māori Party had been trying to negotiate a compromise between the government and Māori.
Labour and the Greens both support the sanctuary, but not at the expense of Māori rights.
New Zealand First pulled its support for the legislation last year on the basis the the sanctuary breached a 1992 Māori Fisheries Settlement.