Gareth Morgan has quit The Opportunities Party (TOP) after a dispute over how to spend a $50,000 donation that the party has given back to him.
But Morgan says the main reason he is leaving is not the dispute, but simply because it is time to pour energy into other projects.
Morgan has donated about $2 million to TOP to contest the 2017 election, and said he had put in about twice that amount overall, including what it took to set up the party from scratch.
"Obviously they're quite keen for me to just give them money, but that's not happening," Morgan told the Herald.
"It doesn't matter where I'm spending money, I very much demand accountability ... The response was pretty wishy-washy, just general paying ourselves wages, whatever, and I thought, 'Whoa, no no no, that's not happening'.
"They just wanted someone to write them a cheque."
TOP leader Geoff Simmons said he had no idea what Morgan was referring to.
"That's certainly not what the email trail says ... The reason for returning the [$50,000] money was Gareth wanted to call off the leadership election, and we didn't want to because we wanted to democratise the party."
Asked if the party had been a dictatorship, Simmons said: "Gareth was the sole funder, the leader, and chair of the board. I'll let you draw your own conclusions."
Morgan set up and led the party in the 2017 election, when TOP won 2.4 per cent of the party vote. He stepped down as leader after the election, but he stayed on in the policy team.
He was a controversial leader who once referred to Prime Minister Jacinda Ardern as having to prove she's more than just "lipstick on a pig", told TOP candidate Dr Jenny Condie she was a "pain in the arse" and should quit the party, and was critical when Ardern's cat Paddles was run over as others offered sympathy.
Simmons said Morgan provided plenty of policy heft, but "on the communications side, we'll be aiming for a bit more cheek and less arse".
Morgan said he had no regrets about any of his comments.
"That's my approach. You drop a bomb and get people's attention, and then you have a rational discourse. I dropped a few bombs, deliberately, especially when the Jacinda phenomenon came along and 20 per cent of the vote moved in 48 hours.
"Then you realise how trivial politics is. Policy's not even relevant to 90 per cent of people. It's all X-factor, feel-good garbage. That's not my space."
He said funding and leadership were both important.
"In my view, the leadership cannot be kumbaya, 'let's hold hands' - that's Green Party-type stuff. For me, it's got to be hard-ass, straight between the eyes, 'this is the best policy and tell me why it's not, otherwise adopt it'.
"Geoff is far more conciliatory. He's a really nice guy. He and the others, well, they're not going to be like me. They'll adopt a different approach, and whether that works I have no idea, but it's up to them."
Simmons won the leadership contest at the end of last year, despite Morgan backing his rival Amy Stevens.
But Morgan said that had nothing to do with his resignation.
"I've so many other things I want to be doing. It's all absorbing, this stuff, and I'm just not prepared to be a Winston Peters and spend my lifetime doing it.
"You've just got to pass the baton to the new guard and not lurk in the shadows behind them. Even if people perceive that you're still running it, it doesn't give the people running it a fair go.
"I'm full noise, money's there, effort's there 24 hours a day - that's how I've done all the projects I've ever done. To be sort of half-in doesn't really fit with my character."
TOP will now have a financial void to fill, and Simmons said he was "optimistic" the party would raise enough money to fight the 2020 election.
He thanked Morgan for creating the party.
"We will always be grateful to Dr Morgan for the initial momentum he provided."
Morgan said he had enjoyed the ride.
"I loved it. It was good fun. Next project - I'm back into making money, which I find a lot easier.
"I'd always given myself a couple of years to set the thing off. I had to do it because otherwise I wonder what would have happened. Well, I know now."