A dispute over ministerial positions is delaying Winston Peters' announcement, NBR reports.
They report that NZ First has requested from National four Cabinet roles and one ministerial position outside Cabinet in return for support.
National had planned on offering three positions - and not all of those would be in Cabinet.
NBR understands Peters has baulked at this - and he went back to Labour seeking more ministerial roles than National would offer.
One of Winston Peters' advisers, Paul Carrad, came over to check out the Beehive Theatrette and to place a platform behind the lectern for Peters.
However, reports say this platform was soon removed.
Previously, Peters returned to considering his coalition options behind closed doors, after a short lunch break and revealing things are still changing "by the hour".
"We are not very far away from finality and we are just going to have a bite to eat and put it all on the table and make a decision," he said on his way to lunch at a Vietnamese restaurant in Lambton Quay.
The NZ First leader said the deals at this stage were "seriously substantially final".
Asked if there was a chance a decision might not be made today, Peters said he hoped not: "We've set our minds to make a decision. The reason why I don't rule out things is you never know what might blow in the next couple hours.
"That is the nature and shape of politics. It always has been.
"Things change by the hour."
Asked about how the announcement would be made, Peters said his focus was on the decision and not how it would be announced.
He had not decided whether he would tell both parties before the announcement to New Zealand.
"Our total focus has been on the decision.
"Other matters are extraneous and will sort themselves out once we have made the decision."
Peters said the decision was "seriously difficult".
"There are pros and cons for every part of this decision we have got to make. And we have one more chance to evaluate what it means, both ways."
Peters said his fellow MPs were feeling the responsibility.
"When you are going into discussions with grave uncertainties that are both personal and as a group of people, it is a very, very anxious time."
Peters said no negotiation ended up perfectly. After he had "some breakfast", Peters said NZ First would go back into discussions amongst its caucus.
"We have a few hours to go. But we hope to complete it."
Earlier today National leader Bill English also indicated there was still room to amend its policy agreements with NZ First.
Changes were possible up to the very last minute, English said before heading in to meet his MPs at 11am.
The caucus meeting was to get the approval of his MPs to the agreement in advance of Peters making his decision between National and Labour.
He would not comment on the content of that agreement but asked if he had decided on Cabinet positions yet, said "that has been discussed as part of the agreement."
English said there was always the possibility of further changes and there had been "a lot of progress in the last 24 hours."
"This is a process where further discussion could be had, but I'm satisfied we are in a position where I can present to the caucus and the National Party board the broad outline of the agreement."
The agreement National had reached with Peters after "intensive negotiations" would be the basis of a strong and cohesive government.
"Later in the day Mr Peters will indicate whether he agrees with that."
English said he had not considered whether he would resign if Peters did not opt for National.
He did not know how Peters intended to handle the announcement, saying there would be discussions during the day about those logistics.
He was seeking the caucus and board approval now so that if there ended up being a NZ First - National government he could go ahead to form that.
Whanganui's Carmen Walker died following complications during a hospital procedure.