Metiria Turei has resigned as co-leader of the Green Party.

She says the party did not ask her to resign - and as recently as last night, the executive gave her a vote of confidence.

Just yesterday Turei said she would stay on as co-leader after two senior MPs resigned in protest on Monday over her continued leadership of the party.

But a poll to be released tonight is understood to place them in a precarious position, possibly as low as five percent.

Turei has been under growing pressure after she admitted to historical fraud while on the benefit 20 years ago.

She will withdraw from the party list but will still stand as a candidate in the Te Tai Tonga electorate.

Turei told the media she is confident if she steps aside, the Green Party will have the best possible chance of improving its vote and being part of the next government.

She said the questioning of her family since her admission of fraud has been intrusive and unnecessary, and she has a responsibility to them.

"For them and myself it's intolerable. I can deal with the political scrutiny, I've been doing that for a very long time now, but that scrutiny of family members is just not acceptable."

In a statement to the media, James Shaw paid tribute to Turei.

"For the battles that she has fought, for the sacrifices she has made, and for the lives that she has changed, the Green Party thanks you."

Shaw will remain the party's sole co-leader until next year's annual general meeting, when the Greens will elect a new female co-leader.