Green Party co-leader Russel Norman says it is too early for Labour MPs to make a call on what position he could hold in a government with Labour.
Two of the MPs vying for the job as the new Labour Party leader, Grant Robertson and David Cunliffe, have ruled out making Dr Norman finance minister if they are in a position to form a government with the Greens after the next election.
Dr Norman says it's a matter for post-election negotiations and will depend on how the votes fall.
"It's about relativity between the parties; I think that's the key issue."
He says another possibility in an arrangement with Labour would be for the Green co-leaders to share the role of deputy prime minister.