Jacinda Ardern has revealed she held out for a week - refusing daily - before finally agreeing to replace Andrew Little as Labour's leader.
She has given her most detailed account so far of what it was like to be nominated for the party leadership.
She was talking to teenage solo mums at their school in Wellington today.
Ms Ardern said she was at a Rotary meeting in the capital on her birthday, July 26.
"I'm going to remember that day for a long time," she said.
"Rotary gave me a great big birthday cake - and it was on that day that Andrew (Little) said to me 'I'm worried about the polls and wondering whether you should do this job instead'.
"It's two months, almost to the day, since that happened, and a couple of days later he made the decision to stand down and he nominated me as leader of the Labour Party.
"And I can tell you that from the 26th of July to the 1st of August, every single day I was asked and I said 'no, no, no'.
"There were lots of reasons for that, but the moment when Andrew made that decision, then there was a role I needed to step into and there was no doubt in my mind that that was what I needed to do."
Ms Ardern said the best message she could send to young women was: "When opportunities come up, say 'Yep, I can do that job'."
