A poll commissioned by the New Zealand Taxpayers Union and conducted by the National party's preferred pollster Curia has the opposition slumping to near-record lows.

With 46 per cent, Labour more than doubled the support of National, on 21 per cent.

Minor right-wing party ACT jumped to 15 per cent, with the Greens on 10.

Translating the results into parliamentary representation, Labour and the Greens would be able to govern with a combined 70 seats.

Ms Ardern, who has not trailed in a poll for 18 months, said her focus was New Zealand's COVID-19 outbreak.

"Someone mentioned the numbers to release today, I can't actually recall them ... that probably gives you a bit of a sense of where they're sitting in my order of importance right now," she said.

"Right now I have a pretty singular focus."

The polls could spell trouble for Ms Collins leadership of the National party.

Ms Ardern out-polls Ms Collins 51 per cent to just four as preferred prime minister, with ACT leader David Seymour on nine per cent.

NZ Herald political editor Claire Trevett writes the poll "may well prove catastrophic" for the embattled 62-year-old.

"They cannot simply brush off a poll from their own pollsters," she wrote.

"The two criteria already being talked about as the trigger for a leadership coup within National was for National's polling to be less than 26 per cent and Act to be heading toward 20."

A second poll, which was not released publicly, showed a similar position.

The private poll conducted by Labour's pollsters Talbot Mills showed Ms Ardern's governing party in a similarly dominant position.

News outlet Stuff reported that survey had Labour in front with 45 per cent, and National on 26 per cent, with ACT polling 13 per cent and the Greens just six.

New Zealand isn't due for an election until the second half of 2023.

Australian Associated Press