Christopher Luxon says Prime Minister Jacinda Ardern's "arrogant prick" comment in Parliament shows she's under pressure as the election ticks closer.
The moment occurred just after Ardern answered a question from ACT leader David Seymour about how she handles mistakes.
After answering, Ardern sits down and Speaker Adrian Rurawhe begins to call the next question. Ardern's microphone remains live and she can be heard saying: "Such an arrogant prick".
Appearing on AM on Wednesday, Luxon defended Seymour saying he's not an arrogant prick.
"David was my neighbour for many years. He was a very good neighbour. I can tell you that," Luxon told AM co-host Melissa Chan-Green.
"He was very well-behaved, kept his music under control and I found him to be actually a very dedicated public servant and also very deeply involved in policy development."
Luxon described Seymour as a "very thoughtful young man".
When asked by Chan-Green if he had ever made a remark in private that he wouldn't want someone else in the House of Representatives to hear, Luxon said "I'm sure I have".
"The comments were a bit unedifying yesterday. I think the great thing is the Prime Minister apologised very quickly," Luxon said.
"David [Seymour] accepted it in good grace and frankly it just speaks to the Prime Minister being under a bit of pressure at the end of the year or through the whole year frankly."
When pressed if he's ever made a comment about other politicians to National's deputy leader Nicola Willis, Luxon said he's aware that the microphone is on the whole time.
"I think it's a good reminder that it actually is. So I've tried not to say unedifying remarks in the house," Luxon said.
With the election under a year away, Luxon hopes it doesn't get heated between National and Labour.
"I think one of the great things about New Zealand and our politics is that we can actually disagree with each other without it becoming deeply personal or disagreeable," he said.
"I know we are going to have robust exchanges ... I really hope as we go into next year, we can focus on the actual differences that we have around policies rather than actually getting into the petty politics of it all."
Watch the full interview with Christopher Luxon
