Dame Annette King has revealed she was in tears when she and other Labour MPs tried to roll Helen Clark in the 1990s.
The veteran former MP, now New Zealand's High Commissioner to Australia, is the subject of a new biography by former press secretary John Harvey and political reporter Brent Edwards.
The book's being promoted as a warts-and-all look back at her career in and out of Parliament, from the economic reforms of the 1980s right up until the 2017 election.
Dame Annette told The AM Show on Thursday part of the book deals with Labour's lowest point of those three decades - 1996.
"We'd reached something like 15 percent in the polls - NZ First were ahead of us in the polls, the Alliance were almost the same as Labour on 12 percent. Helen [Clark] I think was on 2 percent.
Not even during David Cunliffe's reign as Labour leader - which Dame Annette describes as "disastrous" did Labour sink that low.
"Five of us went to her and said, look - the election's only months away. This is about May 1996. We said we're going to lose, we're going to lose the party and you need to go."
Dame Annette, future leader and present Auckland Mayor Phil Goff, future Finance Minister Michael Cullen, and MPs Jim Sutton and Koro Wētere confronted Ms Clark.
"It was a really sad moment - it wasn't that she wasn't working hard and trying hard. We were just going nowhere. I can remember sitting there with tears running down my face, saying, 'You're going to have to go. We have to save the party. We're being killed.'"
But with no one obvious to replace her except Mike Moore - who'd already led Labour into an election loss - Ms Clark stood her ground.
"She stared us down, and she basically told us to get on our bike and go."
That was May. By October, Labour had reversed its fortunes - they finished up with 28 percent, only 5.5 points behind National.
"Of course Winston [Peters] was the kingmaker, and he went with Jim Bolger."
But Ms Clark had the momentum, and Labour would go on to trounce National in the 1999 election - and Ms Clark would lead the Government for the next nine years.
"I've often credited that moment in history - if you look back, you saw Helen came out and showed the steel she had to be the leader she was."
Across the ditch
Dame Annette was appointed High Commissioner to Australia in November.
"I'm enjoying life. I'm very happy in Australia and I like Australians," she said. "Fantastic weather. Hot, dry days and I'm told a very cold winter, which is like Christchurch - and I like a cold winter."
She spent 33 years in national politics - 15 of them in Government, 15 in Opposition and three outside of Parliament.
"I don't miss Parliament. I miss the people - that place is full of wonderful people and you make friends. So I miss them, but no - I was ready to go. I'm enjoying life and I'm enjoying Australia and I'm loving the job I've got... there's life in the old girl yet."
She says the biography will be "uncomfortable" reading for some.
"There was no point doing a book that was going to be sugarcoated. I've told it as I saw it, and people can disagree if they saw it differently... The good times and the bad times, in Government and Opposition."