Christopher Luxon says ACT and New Zealand First have agreed to the policy programmes each party has with National, with the only remaining issues being ministerial responsibilities.
"We have made great progress. We have just got to dot some 'i's and cross some 't's on most of the agreement. The only outstanding issues are ministerial responsibilities. We are in conversations with both party leaders about those positions today and late last night."
He said the policy programmes have been closed out with all three parties.
"We have got three parties all agreeing with each other's policy programmes as well and we have now agreed how we are going to operate in Cabinet and how we are going to work together."
On Monday, Luxon announced that National had policy programmes agreed with ACT and New Zealand First and he was leaving those parties to look over each other's deals with National.
Earlier on Tuesday, ACT leader David Seymour said he believed the second-largest party of the three forming a coalition should provide the deputy Prime Minister role.
"I think there is a clear case for that to happen," he said.
"But like I say, you are involved in a negotiation and there are lots of different options and things to talk about. I am not going to try and predetermine it one way or another, but that is the negotiation we are engaged in."
Seymour also said proportionality was important and suggested ACT should have more ministers than New Zealand First.
Luxon wouldn't comment on that when he arrived at the Cordis Hotel on Tuesday afternoon for meetings, but he did say Seymour had "probably got out and ate a lot of Weet-Bix this morning.
"I do my conversations in the room as you have observed and when I say I do something, that's how we do it."
The Weet-Bix remark is a reference to a comment Seymour made on Monday night. After Luxon announced that National had agreed policy programmes with ACT and New Zealand First, Seymour said Luxon had maybe had too many Weet-Bix that day.
Luxon said the Deputy Prime Minister role wasn't a sticking point.
"I wouldn't say that, no. I would say we have got to start a conversation about the full set of ministerial appointments and make sure we have got the right people in the right places."
It is a ceremonial role, Luxon said, and for when the Prime Minister is unable to perform their duties, such as when they are overseas.
Luxon said National wanted "to move quickly" with deciding the ministerial appointments.
He wouldn't put a timeline on the negotiations but said the parties were working with urgency.
Luxon is currently meeting with New Zealand First leader Winston Peters.
Peters wouldn't speak to media when he arrived at the Cordis Hotel. Newshub tried to ask him about the Deputy Prime Minister role.
Luxon met with Seymour at his Auckland home on Tuesday morning.
Speaking afterwards, Seymour said there was a lot of negotiating going on but the pair had made "really good progress". It was "collaborative and constructive".
"We have had to talk a lot about policy, but we have also got to have a Government formed and that involves people having to do jobs that align with the policy goals of the Government as well as their own skills and passions so they can deliver for people."
Seymour said the meeting focused on "the shape of the Government" rather than policy.
He wouldn't say what ministerial roles ACT was after or how many ministers ACT would have.
"To be honest, I could start giving really excruciating detail, but I know if I did that, you would just start asking more questions. I know how you operate at Newshub. You are just newshounds."
He wouldn't say whether it was possible for a Government deal to be struck on Wednesday.
"I think it is always possible we are going to get a deal tomorrow, but I feel bad for having said that quite a few times in the last five weeks so I won't say it today."
But he "absolutely" thinks it will be this week.
