It's the second day of negotiations to form the next Government and NZ First leader Winston Peters is looking at a marathon session.
NZ First will meet with National at 9:30am on Monday and Labour at midday.
"All day Monday and into the night," he told reporters after holding the first round of talks with National and Labour on Sunday.
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Those meetings lasted just over two hours, but Mr Peters has set Thursday as the deadline for a decision and says there are complex policy issues still to deal with.
He wants concessions from the main parties in return for his support, and he'll be weighing up what they offer when he comes to deciding which of them is offering the best deal for his party.
Prime Minister Bill English and Labour leader Jacinda Ardern headed their negotiating teams on Sunday and after the meetings both said theirs had gone well.
As the leaders handle the top-level talks there are reports of intense behind-the-scenes activity to thrash out policy agreements.
National and Labour have been preparing for the talks since the election, and they've both done the groundwork on the differences and similarities of their policies when they're put up against NZ First's.
Mr Peters is believed to have an extensive list of NZ First policies he wants implemented, ranging from immigration cuts and regional development to enhanced SuperGold Card entitlements.
The meetings are taking place in a neutral venue at Parliament, and security around them is being tightened.
All three teams have agreed the negotiations will be strictly confidential.
Mr Peters wouldn't begin formal negotiations until final election results had been announced. They came out on Saturday, confirming that neither National nor a Labour/Greens alliance could command a parliamentary majority without NZ First.