Parliament needs people like Metiria Turei - James Shaw

Green Party co-leader James Shaw says Metiria Turei's welfare story was controversial but essential to start a conversation about poverty in New Zealand.

Mr Shaw told The AM Show on Monday he is confident she's told the full story, and believes Ms Turei should be a Cabinet minister.

"Parliament needs people like Meitira Turei in there to represent people who are living below the breadline," he said.

"[We] need people who have experienced it first-hand."

The Green Party has struggled to control the message after Ms Turei disclosed she committed welfare fraud as a young mother. Ms Turei told the crowd at a policy launch three weeks ago that when she was a 23-year-old single mother she failed to disclose extra flatmates to WINZ so she could collect a higher accommodation supplement.

Ms Turei shared the story when the Greens announced plans to raise benefits by 20 percent, but the policy has been obscured by Ms Turei's divisive confession.

The Green Party enjoyed a (pre-Labour Party leadership change) boost in the polls, coupled with eventual condemnation from Labour.

That boost is threatened by two further revelations: firstly, that one of Ms Turei's flatmates was her own mother, and secondly, that she committed electoral fraud - Ms Turei was enrolled in Mt Albert so she could vote for a friend who was running against Helen Clark for the McGillicuddy Serious Party.

Mr Shaw said Ms Turei had told him everything and there are no more revelations to come. He said he "knew about her mother", but said Ms Turei had "completely forgotten" about the enrolment. 

"Here is the story of someone who has come from nothing, who got out of those circumstances, became a lawyer and entered Parliament to become the co-leader of the third largest political party in New Zealand.

"So whatever happened in her early life, the woman I know is of extraordinary honesty and integrity."

On Friday, Ms Turei announced she would forfeit a ministerial position, should Labour and the Greens win the election.

Labour Party leader Jacinda Ardern told media her staff had relayed to the Greens that Ms Turei would not be appointed Minister in a Labour-led Government. 

But Mr Shaw said when that message arrived at the Greens' camp, Ms Turei had already made her decision. 

"I believe that she should be a Cabinet minister, but it was her decision, and it was her decision originally to share her story. At the time, she said that she knew that this was a risk.

"It's a controversial story, but if we don't have the conversation then the system will stay broken."