Looks like there was a poll out already:
A TVNZ Colmar Brunton poll published on 25 August found David Cunliffe led the potential contenders with 29% of the popular vote and 32% of Labour Party members, followed by Jacinda Ardern on 15%, Shane Jones on 11%, Grant Robertson on 10% and Andrew Little on 9%
http://tvnz.co.nz/politics-news/grant-robertson-confirms-bid-labour-leadership-5543300Interesting, Jacinda Arden, who has not declared, ranked second amongst total kiwi's but 4th among Labour members.
- Cunliffe was the most attached by Key, esp over possible gov't with the greens Russel Norman (this came acorss as a huge no no, what's the deal with the greens being demonized by Key?)
- Robertson being gay was mentioned as a possible hindrance to his bid, even by former MP Georgina Beyers (first trans MP anywhere)