However, Labour is understood to have offered fewer ministerial positions than National - and that has prompted further negotiations over the course of the day.
Greens leader James Shaw has told Newstalk ZB: "There will be a delegate conference call tonight. The vote will be on our proposed agreement with Labour. I have no comment on whether NZ First are likely to go with National or Labour."
Newshub reported sources saying Peters had visited Labour's offices twice during the course of the day and the NBR has also reported it was negotiating for more ministerial posts.
NBR reported that NZ First had sought four ministerial positions in Cabinet from National and one outside but was offered three in total.
The NZ Herald was told Labour's agreement had offered fewer positions than National.
NBR said NZ First wanted Peters, deputy Ron Mark, Tracey Martin and Shane Jones in Cabinet with a ministerial role outside Cabinet for Fletcher Tabuteau.
The Green Party has called a teleconference meeting of its delegates at 7pm where they will be asked to agree to a deal between Labour and the Greens.
While it had previously held a space open for those conferences, they had been cancelled by mid-afternoon each day. Today's is still scheduled to go ahead.
It is understood the parties wanted Labour to get its deal with the Green Party signed off before or as soon as possible after announcing NZ First's decision.
The Green Party requires at least 75 per cent of up to 150 delegates to agree to the Green- Labour deal. The quorum for that is 50 per cent of delegates from at least half of the electorates.
National's caucus met this morning to be briefed on the talks. Ahead of that meeting English said they would be told only the 'broad parameters' of it.
He would not comment on the content but said Cabinet positions were discussed with NZ First.
There was always the possibility of further changes and there had been "a lot of progress in the last 24 hours."
He believed 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.
Labour has also had a caucus by teleconference to update them but Labour's rules do not require caucus signoff.
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.
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."
English indicates there's still time for tweaks
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.
