Mr Key told TV3's Firstline today that he did not mind who was leader, saying they all had strengths and weaknesses.
He said Mr Jones would not make it and the race would be between Mr Robertson and Mr Cunliffe.
"Both of those gentlemen are going to take the Labour party even further to the left ... It's going to be quite a far-left opposition between the Greens, who are a long way left, and Labour who are tracking left.
"So in a way, you know, I don't really care because I think people will vote on the policies, and in the end it will be a centre-right Government of six years of proven quality, versus a kind of far-left opposition.''
Mr Key said the race was between three camps who "all hate each other''.
"So all we're going to see is three weeks of how deep the divisions are. Then at the end of it, there will be this magnanimous speech of how unified they all are. And actually they'll retrench to their corners and all hate each other again.''
Mr Cunliffe told Radio New Zealand this morning he was humbled by the level of support he had, but the race would be "really competitive''.
"It's a good thing for the party and I've got two very able colleagues that I'm racing with, and we're going to be working together after the race. But of course the big picture is, who can win the country.''
Mr Cunliffe said support for him and the others was even within caucus - but he was comfortable with his level of support around the party base.
"This is about what is best for the country and best for the party as a whole, it's actually not about the individuals. We're only there to serve the group.''
Asked what he could do that former leader David Shearer could not, Mr Cunliffe said that was for others to judge.
"But the feedback I'm getting is that I'm pretty high energy, I'm willing to lead from the front, call a spade a spade and help the party move forward in debate against John Key's National party.''
Questioned on how the shift to the left would affect middle New Zealand voters, Mr Cunliffe said Labour needed to earn the confidence of the labour movement first.