The Green Party has plummeted below the five per cent threshold it needs to return to Parliament while Labour has soared in the first political poll since former Green co-leader Metiria Turei stepped down.

The One News Colmar Brunton poll has the Greens on just 4 per cent while Labour has rocketed up from 24 to 37 per cent in the first Colmar Brunton poll since Jacinda Ardern took over as leader.

The Greens are just short of the five per cent party vote needed to get over the threshold to return to Parliament.

The poll shows the change from Andrew Little to Ardern as leader has worked for Labour to recapture support. It is seven points adrift of National which was also feeling the strain, dropping from 47 to 44 per cent.

Ardern had rocketed up to 30 per cent as preferred PM, even with National leader Bill English.

The poll was not as bad for NZ First as the Greens - it was down from 11 per cent to 10.

THe Maori Party had nudged up to two per cent and Gareth Morgan's Opportunities Party was steady on two per cent.

The One News Colmar Brunton poll of about 1000 voters has a margin of error of +/- 3.1 per cent.

The result is devastating for the Greens which until the ructions of recent weeks had been polling around 10-11 per cent. It is now fighting for its survival nearly five weeks before the election.

It will go into the election campaign with only one leader now - James Shaw who is a first term MP and a relative rookie compared to Turei.

Parliament wound up on Thursday and the leaders will head out onto the hustings. Labour's campaign launch is this Saturday.

In the lead up to the poll, Ardern announced Labour's Auckland transport policy of light rail from the CBD to the airport to be paid for by a regional fuel levy for Aucklanders. She also announced policy to charge for the commercial use of water to pay to clean up waterways.

That angered rural sectors and Labour was forced to clarify the size of the levy after initially saying it would not do so until after the election. The dressing down by Australian Foreign Minister Julie Bishop over Labour MP Chris Hipkin's involvement in the citizenship case of Australia's Deputy PM Barnaby Joyce was happening at the end of the polling period.

National also announced a big Auckland transport policy, a mental health package, and a law and order policy on youth offending including a 'Military Academy' bootcamp for serious youth offenders and fines for parents whose children under-14 years were caught on the streets between midnight and 5 am.

The Green Party usually polls at about 10 per cent, but that support spiked to 15 per cent in the last poll at the end of July.

That was in the immediate aftermath of Turei's admission she defrauded the welfare system as a solo mum in the 1990s by not disclosing flatmates.

That sparked a dramatic series of events including the change over from Andrew Little to Ardern as Labour leader after Labour's polling dropped to the low 20s.

Turei stepped down as co-leader on August 9 and has opted not to return to Parliament after scrutiny of her admission and a further admission she had breached enrolment rules to vote for a friend took its toll.

In a Newshub Reid Research poll earlier this month taken immediately after Ardern became Labour leader on August 1, Labour went up nine points to 33 per cent and the Green Party was down to 8.3 per cent.

Turei stepped down on the same day that poll was completed, saying the scrutiny of her family was too great.