The two Green Party co-leadership candidates are both committed to taking the party leftward if they win at the Stuff Green Party debate.

But while Julie Anne Genter and Marama Davidson agreed on many policy positions they had very different positions on how to grow the party's dwindling vote.

Genter and Davidson are both competing for female co-leadership, a position left vacant after Metiria Turei resigned last August.

Cameron Burnell/Stuff The debate was held in Parliament's old Upper House.

The two will travel the country asking members to vote for them ahead of April 8 when a winner is announced.

READ MORE: Both Green Party leadership candidates express doubt about budget rules

VOTING AGE, A NEW TOP TAX RATE, AND FREE DENTAL

In a lightning round segment both Genter and Davidson said they supported lowering the voting age to 16, but not 14.

They also both supported a new top tax rate on higher income earners and a universal basic income.

But while Davidson was all for using that new money to pay for free dental healthcare for everyone Genter said that would be something "to work towards."

Unsurprisingly for a party hovering just above five per cent, both MPs were keen to see the MMP threshold drop to four per cent.

HOUSE PRICES

Both candidates said making housing affordable would likely involve a drop in prices.

"As naturally we increase the supply of homes then yeah, probably prices will come down relative to income. I think it's very unlikely that we would see the kind of income inflation that would catch up with house prices now it's ten times the average income," Genter said.

Davidson said families were struggling to make rent let alone buy houses.

"If we are not going to lift our incomes then we need to do everything we can to make that rents and housing is affordable and secure," Davidson said.

"[Prices] may end up coming down with the necessary increase in affordable housing and overall housing supply."

MINISTER VS NON-MINISTER

Davidson and Genter naturally have different positions on whether or not both co-leaders should be ministers.

Genter is a minister outside cabinet while Davidson is backbencher.

Davidson said this would be key to keeping the party's brand alive and separate from the Government's.

"I will not have a portfolio under risk or threat with me being able to uphold the political positions that the Greens and our members have demanded we stay strong on - and continue to push the Government beyond its agenda," Davidson said.

Genter argued that any criticism she made of the Government would have more reach because they came from a minister.

"The Maori Party had one leader inside and one outside and it wasn't that helpful to them in the long run," Genter said."

"The case is that ministers end up being in the public eye quite regularly, so it's very easy for the public to understand who we are, what we stand for and what we are already delivering," Genter said.

"As a minister outside Cabinet I'm still able to speak out when there's areas of disagreement with the coalition Government."

"I'm able to demonstrate that we are delivering."

GETTING THE VOTE UP

The Green Party's vote dropped to 6.3 per cent in the last election, down from 10.7 per cent in 2014.

Davidson said growing the vote would require reaching out to communities who the Greens often had trouble with.

"The regions - we could be a lot stronger in the neglect of the regions that has happened," Davidson said.

"[New voters are] coming from working class communities. They are coming from small business and enterprises...They are coming from culturally diverse communities - the diverse reality of a modern Aotearoa is going to be something we will need to reflect in our members our candidates and our supporters going forwards as well.

"I'm really proud to have led the recruitment particularly of more Maori and Pacific young people into the party as candidates and supporters."

Genter disagreed, saying the party needed an evidence based and hardheaded approach to winning back the votes they had recently lost - mostly to Labour.

"To get back to the vote that we had in 2014 we need about 200,000 additional votes. To speak to 200,000 people a co-leader would have to be speaking to a packed out hall of a 1000 people every day of the year," Genter said.

"We need to be realistic that with only eight MPs now our ability to reach out to those communities is even less than it was in the previous six years. I think it sounds like a great idea and I absolutely believe we should be trying to engage with communities that we haven't been before - but I think even just getting back the voters who voted for us in 2011 and 2014 would be a good start and put us in an excellent position to negotiate much greater wins in 2020."

DROPPING DEBT TARGETS FOR 2020

Genter said the Government's target to get Government debt down to 20 per cent of GDP within five years was "bad economics".

The Greens and Labour signed up for the target as part of the Budget Responsibility Rules (BRR) before the last election.

"I don't think the 20 per cent target is grounded in any sound economics, and I don't think it was the right decision for us to sign up for that particular provision," Genter said.

"I think we need to be going into the 2020 election with a very clear and compelling reason why our economic vision is different."

Genter said with low global interest rates and plenty of things the New Zealand Government needed to spend money on, borrowing more money would make sense.

"There's been quite a strong case across the world for governments to be borrowing in infrastructure that has long term benefits like responding to climate change, or solving some of our housing crisis, which will help reduce the high levels of inequality we are facing."

Davidson also expressed doubt about the target.

"The Greens have a particular responsibility to push beyond the narrow confines of things like the BRR rules...We are the most economically progressive party in Parliament."

"People are waiting for a better economic narrative that understands the connections to our environmental, our social, our economical wellbeing - that they are all connected."