Todd Muller replaced Simon Bridges as National Party leader in May. Today he resigned. He cited health reasons, and commentators including PM Jacinda Ardern have said politics was a hard job.
Muller said the role has taken a "heavy toll on me personally, and on my family, and this has become untenable from a health perspective".
Bridges took over from Bill English as leader in February 2018.
Prime Minister Jacinda Ardern has passed her best wishes on to Muller and his family.
"No matter what side of Parliament you're sitting, politics is a difficult place," she said.
In a statement, NZ First leader Winston Peters said there was a "heavy price of trying to lead the National Party today".
He said Muller was a good man who would bounce back.
"Leading a divided and incompetent caucus would have tested even the best leader.
"Todd never had a chance given the fault lines of ambition, personality, and ideology that run deep through the National Party caucus."
Former Prime Minister Jim Bolger, who backed Muller's move into the leadership, didn't anticipate his resignation. He told Nine to Noon it must be a traumatic time and wished his family well.
Muller worked in Bolger's office when he was PM.
"I wish the party well. They have to do what Jacinda did the last election ... the Labour Party was wallowing and in despair, and she took over from Andrew Little and they won. She didn't win in the sense of getting more votes than National - Bill English got far the majority - but managed to put a coalition together and Bill wasn't."
He said the party changing leaders twice quite close to an election was "remarkable".
"You need a leader that can focus their thinking across the political spectrum. The leader I'd been looking for is somebody who can refocus the thinking of New Zealand and their own party of course - this applies to the Labour Party as much as to National. Sounds like somebody who can be upfront and honest with the public," he said.
"All political parties are dream-walking at the moment."
Massey University professor and political commentator Claire Robinson said he was naive.
"I think it shows how completely unprepared he was for the role. He obviously thought he was God's gift to the National Party and taking over from Simon Bridges ... and I think he thought it was going to be so easy simply to role out a whole lot of new policies under his leadership and everybody would think: 'Oh good, everything is okay now'."
Political scientist Dr Bryce Edwards said Muller made a horror start to the job.
"He's had a terrible month.
"He has never been able to take control of the narrative - the story around his own leadership. It really looked like he had played the situation very badly - his own party was losing confidence in him, the public was losing confidence ... so it is not surprising."
Palmerston North lawyer and conservative political commentator Liam Hehir said: "Nobody knows what's going on ... it's bizarre and unprecedented."
He said everything was speculation but "the only thing that is clear is what a disaster it is".
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The National Party would now meet to elect a consensus candidate, he said.
"There's going to be total disagreement [given] how fast they have to move, about who that should be."
Hehir said it would be an opportunity for Judith Collins to put her hand up but there would be strong internal opposition to her leadership.
"I would think the best candidate would be somebody that nobody thinks would have long term leadership ambitions ... like Gerry Brownlee."
It would be a challenge for anybody who would take on the role so close to the election, he said.
"It's only about saving the furniture now ... what is disaster control? It's not moving forward, it's stopping the bleeding."
The National Party that was once portrayed as a "cohesive result-oriented party" was just a "myth" now.
ACT Party leader David Seymour said he was surprised.
"Todd Muller is a hell of a nice guy.
Seymour said he had vast business experience.
"Being a leader of a political party on the national stage is an extremely competitive and bruising role.
"You just have to look at the human side of politics and say 'he gave it a go, good on him' and respect his decision."
He said from ACT's point of view, National needed to pick a leader.
"I will have worked with five National leaders by the end of this week ... hopefully not six by the end of this election."
His role was to ensure ACT was a big party so as to have a chance at changing the government, he said.
Many social commentators said Muller's health was visibly declining.
I don't believe politics has to be as brutal as it is. It shouldn't be a blood sport. We need leaders with courage and integrity. In my experience, when you tell the truth your heartrate goes down, not up. https://t.co/4wZOlPs66b— Sacha Coburn (@SachaCoburn) July 13, 2020
I think there's a big lesson that National has still not learned. They need to cooperative when it comes to the response to Covid. Contrarianism is not currently a vote winner, guys.— Nathan Simms (@5WinstonSmith5) July 13, 2020
Todd Muller was too nice for politics! That’s why cold hearted assassins like *checks notes* Jacinda Ardern are Prime Minister— James Macbeth Dann (@edmuzik) July 13, 2020
I can’t reconcile the Todd Muller who has worked so carefully to meet so many people ahead of becoming leader -just resigning? #nzpol either it’s a seriously dysfunctional & hostile caucus, more to come? -just never let me hear anyone call women ‘part-time’ leaders again— Bronwyn Hayward (@BMHayward) July 13, 2020
I feel sorry for Todd Muller. Brutal game.— Neale Jones (@nealejones) July 13, 2020
The resignation of Todd Muller points to how difficult politics and public life is. Important people recognise and be with that (no matter Your taste) these people step up because they want the best for NZ and I am grateful for that.— Richard Pamatatau (@RPamatatau) July 13, 2020
Respect to Todd Muller for stepping down in order to maintain health and family as his priorities. Whatever political side of the fence we sit, I think we need to just recognise the human behind the media character and applaud a call which would have been difficult and humbling.— Dave Grant (@_DaveGrant) July 13, 2020