Christopher Luxon had downplayed the chance of a confidence-only partnership with ACT following October's election.
Last week, ACT Party leader David Seymour floated the idea of a new kind of governing arrangement if National refuses to cooperate during post-election negotiations.
It comes after National ruled out some of ACT's policies, including repealing the Zero Carbon Act and the proposal to redefine Treaty of Waitangi principles.
Seymour said if National wouldn't "fully share power", ACT would consider a minority-government position.
"We're prepared to do it if the alternative is taking the baubles of office and letting our voters in New Zealand down. So yep, I've done it before - I turned down being a minister to do End of Life Choice," Seymour said.
If this were to come to fruition following October's election, it would mean ACT would support National in forming a government, but they could refuse to support spending initiatives.
The traditional "confidence and supply" agreement is when minor parties guarantee to support the bigger party's Budget.
When asked about this on AM on Wednesday, Luxon, the National Party leader, said that agreement wouldn't happen.
AM co-host Ryan Bridge asked if he would rule out entering that type of agreement with ACT. Luxon wouldn't, instead saying "It's not going to happen".
"I'll tell you why it's not going to happen, David Seymour and I have a good relationship," he said.
"David Seymour and I are very aligned around we need to change the government, we need to sort the economy out, we need to sort law and order, health and education."
When pressed again about why he refused to rule it out and if Seymour is "bluffing", Luxon said it won't happen because "David and I talk regularly, and we have a good relationship".
"We have differences on policies and the means by which we deliver some of those ends, but we will be constructive, mature, responsible and we will make it work," Luxon said.
"That's important because on the other side of this, we need a strong, stable government, good economic management, given the disaster we saw yesterday."
The latest Newshub-Reid Research poll showed National and ACT could comfortably form a government together.
The poll showed a coalition of National and ACT would get 66 seats compared to the left-bloc of Labour/Greens/Te Pāti Māori who would get just 50 - well short of the 61 seats needed for victory.
When asked by Bridge if soft Labour voters who could potentially vote for the National Party should be worried about how right he would go, Luxon urged people to vote National if they wanted a change of Government.
Luxon told AM he considers himself a centrist and a pragmatist and came into politics to solve problems.
"I am sick and tired of us talking about stuff and not getting things done," he said.
Watch this part of the interview with Christopher Luxon above.
