The leader of the newest political party is confident he'll get enough support to enter Parliament at the next election.

Sustainable New Zealand launched yesterday, with former Green Party member Vernon Tava at the helm.

Tava told Mike Hosking there's a large band of voters - around 10 percent - who change who they vote for at each election.

"We think those people are, for a party like us that's in the centre, neither left or right, talking about the environment which everyone cares about, we're well placed."

He says they're setting out to be a "five percent plus" party - and aren't waiting to be offered a seat by National or Labour.

"But ultimately look an MMP system, I think we need to look at any possibilities, but we certainly not going for the 'let's take a seat deal' approach."