The first TVNZ-Colmar Brunton poll since Todd Muller replaced Simon Bridges as Opposition leader shows support for the Labour Party plunging during a horror week of covid-19 quarantine blunders, but still comfortably able to govern without coalition partners at 50 percent support.

That is nine percentage points below the last Colmar Brunton poll, conducted immediately after the Budget and as New Zealand began to emerge from lockdown, when Labour was polling at historically high levels.

The latest poll was taken between June 20 and 24 at the end of a week-long string of revelations exposing holes in NZ's covid-19 quarantine system that the government has been scrambling to plug since then.

If the poll was translated to election night, Labour would command a four-seat majority in the Parliament without needing coalition partners.

National picks up nine points to poll 38 percent support, a respectable first showing for Muller, who regarded 35 percent as a number below which it was legitimate to question previous leader Simon Bridges' continuation in the role. 

It is also one percentage point higher than the 37 percent support that allowed Jacinda Ardern to form a Labour-led government after the 2017 election. Muller also enters the poll with 13 percent support as preferred Prime Minister, one point higher than his predecessor, Simon Bridges, ever managed to achieve in his 27 months leading the party.

Bridges was rolled after taking National to 29 percent support in the May Colmar Brunton poll, a result mirrored in other public and private political party polling. He had sunk to 5 percent support as preferred Prime Minister as measured by Colmar Brunton.

The worst news in this poll is for the NZ First party, measuring just 2 percent support, compared with 3 percent a month ago. A political party must win 5 percent of the so-called party vote under NZ's MMP proportional representation voting system to be guaranteed parliamentary representation. If it cannot muster that, winning a territorial electorate is the only route to a presence in the Parliament.

Asked by One News why he thought NZ First was polling poorly, leader Winston Peters said: "Because your polls are crap."

The party has been throwing its weight around in recent days, being held responsible for the cancellation of Labour's flagship light rail policy until after the election and intervening on law reforms involving commercial rent disputes and evidence rules for sexual abuse cases.

The Act party, which polled 3 percent in this poll, compared with 2 percent a month ago, has a firm grip on the Auckland blue ribbon seat of Epsom, so can expect to gain four MPs. However, in combination of 47 National Party seats, there is no alternative government in waiting on these numbers.

Ardern's preferred Prime Minister status fell nine points to 54 percent.

The poll sought views from 1,007 eligible voters, 404 of whom were polled by landline and 603 by mobile phone, with a maximum sampling error of approximately 3.1 percentage points at a 95 percent confidence level.

This story was amended to reflect the current events that were occurring at the time the poll was taken.