Helen Clark says she knows Vladimir Putin the best among the leaders of the Security Council's Permanent five members - who will effectively decide the next UN Secretary General.
She frequently met the Russian leader at Apec summits when she was Prime Minister of New Zealand, she told the Herald in an interview about tactics in the next part of her campaign to win the top post.
While the P5 leaders are off-limits to Helen Clark, she has met all of them except British Prime Minister Theresa May.
She has shaken hands with US President Barack Obama and French President Francoise Hollande.
She has had more to do with President Xi Jinping of China, having shared a speaking platform with him in Beijing last year.
"Of all the five, the person I would have spoken to most in my life is President Putin because of all those Apec summits that we went to together," she said.
"There were at least two occasions that I sat next to Mr Putin at a dinner and at a lunch. That's the person I've had most contact with because he goes back to my era as PM.
"I thought we had very good conversations at Apec."
She travelled to Moscow and Beijing to discuss her candidacy with their foreign ministers and this week is planning to meet the French foreign minister in New York and British Foreign Secretary Boris Johnson.
John Key said today that in his meeting with new British Prime Minister Theresa May, he hoped Britain would be a champion for Clark within the P5.
The P5 traditionally do not say who they support but it is thought the United States' preferred candidate is Argentinian Susana Malcorra and that Russia's preferred candidate is Bulgarian Irina Bokova.
The last of the indicative ballots will be held next Monday before the first one in October in which P5 members will indicate through different-coloured ballots which candidates might attract a veto from them.
Asked if it was her view that the P5 wanted a person who was more "a Secretary" than "a General" she believed some of them were in the market for more leadership skills.
"It's not that they want someone who going to be on 1st Avenue [the UN address] with a megaphone which isn't my style anyway.
"But I think there is some [feeling] - greater in some quarters than in others - that the UN has to do better and that will take more leadership skills than we have seen in the past.
"In the past generically," she said qualifying her statement, lest she seen to be criticising Ban Ki-moon.
"Traditionally this has been a position which has gone to a diplomat. Is that what it calls for today?"
"You look at what Christine Lagarde has been able to do with the IMF.
"The IMF was a dry, dusty institution."
She said Lagarde's predecessor, Dominique Strauss-Kahn, who resigned over a sex scandal, actually did a good job with the bank.
"And then comes Christine, a really transformational figure, a woman at the IMF starting to be very clear that the IMF doesn't exist in a vacuum, that inequality is a huge challenge to development, gender inequality, income inequality, starts to talk about the impact of issues like climate change on what's going to happen to the world economy.
"So a transformational figure with leadership ability.
"I think if people look at those institutions and say look at what was done, they think 'why not the UN, why not the UN?'"