With less than 24 hours to go until the Green Party votes on finding a new co-leader, the candidates don't know which way it will swing.

AUDIO: Bryce Edwards on the Greens co-leadership election

MPs Gareth Hughes, Kevin Hague, James Shaw, and outsider Vernon Tava are all in the running, but political commentators believe the frontrunners are Shaw and Hague.

They're vying to replace the outgoing co-leader Russel Norman, who announced his resignation in January this year citing family reasons. Norman and Metiria Turei led the party to 10% of the vote in the 2014 Election.

Kevin Hague, now into his third term as a Green MP, is feeling confident, admitting that the race is probably between himself and Shaw.

"I'm not predicting how it's going to go," he said. "I think I have a slight edge, but who knows."

Shaw, a first-term MP who used to work for PricewaterhouseCoopers and HSBC, admits the race could be decided by just a handful of votes.

"It's neck and neck. What we know about the decisions that have been made so far is that it's a very close race," he said.

Gareth Hughes admits that it's unlikely he'll cross the line ahead of his colleagues this weekend.

Hughes, once arrested in a Ronald McDonald costume who became an MP after former leader Jeanette Fitzsimmons resigned, admits most people seem to be favouring Shaw or Hague, but he's not bowing out just yet.

"I think I've got a chance," he said. "I wouldn't describe it as [being] out in front. I've been the underdog throughout the whole campaign, but I'm really proud of the effort I've put in."

Vernon Tava, the only candidate not a sitting MP, has made his pitch by endorsing someone else for the top co-job.

"If we're actually going to reach people who we aren't already reaching, I think James Shaw is the most likely candidate for that," he said.