Greens co-leader Russel Norman is open to a formal coalition in a future government and is interested in senior economic portfolios for himself or Green MPs.
The party won 11 percent, giving it a record 14 MPs in parliament, at the last election.
"I think we can increase that over time," Dr Norman told TV3's The Nation programme today.
He said the Greens could become the largest centre-left party in Parliament over time.
They were "very much open to a formal coalition" after the next election, he said.
"I think the Greens are ready to take on that kind of formal ministerial role," he said.
"The Green team would want ministerial positions," he said.
Dr Norman raised the idea of quantitative easing in the area of monetary policy in a recent speech.
He said the role of finance minister would have to be discussed in a post-election negotiation.
"Obviously we are interested in positions like that but in terms of the detail you couldn't really sort it out until you know what the votes are.
"It is up to the voters to decide how much influence the Green Party has," he said.
As well as economic and finance portfolios the Greens would be interested in social and environmental portfolios.
He said the Greens would work with other parties, including NZ First, when there was common ground.
NZN