Winston Peters once suggested the idea of a shared Prime Ministership with Helen Clark when the Labour Party was trying to form a coalition government, Ms Clark has revealed in a new interview.
It happened after the 1996 election, when MMP had been introduced and the two major parties scrambled to form partnerships with minor parties. National, with New Zealand First's help, eventually came to power.
In the latest episode of Radio New Zealand's The 9th Floor, Ms Clark says the idea of a shared leadership was "loosely floated" by Mr Peters.
"It might've been loosely floated but that wasn't the sticking point - Finance Minister was the sticking point."
She says she can't recall who raised it, as during the coalition talks Mr Peters often had others communicate for New Zealand First through "back routes".
"I don't think it was a serious proposition," she told host Guyon Espiner, saying the idea of sharing the top job wasn't one she could entertain.
"No. You can only have one Prime Minister."
In the final part of the series of interviews with former New Zealand Prime Ministers, Ms Clark talks about her three terms in power which included the decision not to join in the invasion of Afghanistan, the Foreshore and Seabed debate, and the challenge to her leadership.
"We don't have a written constitution so nowhere is it written down what are the powers of the Prime Minister. It's partly your personality. It's the skills that you've got and it's how you use the office," Ms Clark says.
Many New Zealanders might not realise how close Ms Clark's Labour government came to not happening at all, Mr Espiner says.
She had to stare down a challenge from her own MPs in 1996 when her poll ranking for leader plunged to just 2 percent. But she says she comes from "stubborn Yorkshire stock".
"If you want to take me on, take me on, but don't try to intimidate me out because I won't be intimidated out".