Former Green leader Russel Norman labels Marama Davidson's interview 'terrible', won't call her right person for the job

Former Green Party co-leader Russel Norman has hit out at current leader Marama Davidson's "shocker" interview about the party's flagship welfare policy.

Asked on Newshub Nation if Ms Davidson was the right person to be co-leader, Mr Norman didn't answer - and labelled her interview with The AM Show on Monday as "terrible".

Asked how much her party's plans for the welfare system would cost, Ms Davidson admitted that was a "fair question", but couldn't provide a number.

"I don't have the full cost, but reasonable compared to what we lose when we don't allow people to make their ends meet... Too many people are struggling to make ends meet at the moment, and that's not good enough".

But Dr Norman doesn't believe that's good enough.

"She obviously needed to have those numbers. You can't walk in having announced a policy and not know what it costs. I mean that's just not one of the options on the table," he said.

Sticking with a policy introduced by former leader Metiria Turei last year, the party wants to reform the welfare system, including introducing a 20 percent boost to benefits, removing excess sanctions and ensuring access to entitlements.

On Newshub Nation on Saturday, Green co-leader James Shaw showed up with the numbers Ms Davidson didn't have, saying the welfare policy would cost roughly $1.5 billion. However, he also said that number wasn't nailed down and could change as the detail is worked through.

Similarly to Dr Norman, he called Ms Davidson's interview a "shocker".

The criticism from Dr Norman raises further questions about a divide in the party between those backing Ms Davidson's social justice approach, and others pushing a more pragmatic, environment-centred focus.

Ms Davidson has been an MP since 2015, and is from the social justice wing of the party - considered by some to be the heir to Ms Turei. She became co-leader after Ms Turei resigned following revelations she lied to Government agencies in order to keep receiving money in welfare support in the 1990s.

But before Ms Turei's resignation, two other Green MPs quit in protest over her actions, which they labelled as incompatible with Green Party values.

Ms Davidson went on to win party delegate votes in the leadership contest, beating Green MP Julie Anne Genter, who is generally regarded as a pragmatic politician with a focus on transport.

During her campaign for the leadership, several Young Green members threatened to quit the party if Ms Davidson was not elected co-leader.

When asked on Newshub Nation in March if she could be pragmatic and work with Simon Bridges and the National Party, Ms Davidson responded that it would be up to Mr Bridges to move "a lot".

Mr Shaw replaced Dr Norman as the party's leader in 2015. He came from a business background, and has since become the Minister for Climate Change.

The Green Party is holding a leadership meeting this weekend, but Mr Shaw said Ms Davidson's job is safe, despite the interview.

Former National Press Secretary and public relations consultant with Exceltium, Ben Thomas, said the interview was bad.

"For a leader of a major political party turning up without even the costing of their policy, not knowing what current benefit levels were, showing a complete lack of familiarity with a cause she was ostentatiously championing, was a terrible look," he said.

Ms Davidson's appearance on The AM Show also received a scolding by host Duncan Garner.

"I am staggered by the lack of facts and detailed knowledge that she showed in her interview with me this morning...No detail at all".

"She's exposed herself as being underdone at best, and completely incompetent at worst. It's called flaky. I wonder how much longer [co-leader] James Shaw can actually put up with this," said Garner.

National MP Alfred Ngaro said her appearance was amateurish.

"You just jump on public television, you turn around and tell people what you want to do. I just think it's a little careless and the public deserve better than that".