National's public relations machine was spinning less than a minute after revelations the party had fallen to a dismal 25 per cent in the latest political poll - while Labour soared at 60 per cent.

National deputy leader Gerry Brownlee said today the party's own internal polls had it in the high-30s.

National leader Judith Collins labelled the Newshub-Reid Research poll as "rogue" - and Brownlee had sent a press release by 6.01pm on Sunday, backing up his leader's words.

Prime Minister Jacinda Ardern said today she always had a "healthy scepticism" about polls - good, bad or indifferent.

But she believed the latest poll continued a trend of general confidence about the Government's response to Covid-19. She told Newstalk ZB's Mike Hosking she never took the public's support for granted. "A lot can change very quickly."

She confirmed that charging people for quarantine "won't be too far away" - it was not being held up by the Greens, she said. It was a matter of ensuring the legislative practicalities were sorted.

This morning, Collins dubbed the political poll as "ridiculous" and said their own poll had shown them to be closer to the 40 per cent mark. Brownlee also confirmed polling in the "high-30s".

Speaking to Newstalk ZB's Kate Hawkesby, Collins said: "We've seen a big increase in our support since I took over as leader - both in preferred prime minister and party vote.

"I think it's really important that people think about what they're hearing on the ground and what we're hearing on the ground is entirely different.

"Our own polling - which is done scientifically and is done every week - shows a completely different story.

"I'll be making that available to the caucus on Tuesday."

She was coy about that being revealed to the public.

Party leaders receive a confidential, early heads-up on 6pm TV poll results, so that they can provide comment.

"These numbers aren't even in the same ballpark as our internal polls, other public polls and the hugely positive public response to our leader, Judith Collins," Brownlee said in his statement.

"Even with the most rigorous methodology, one in 20 polls will always be a rogue and this is clearly one of them."

Collins has failed to stop the bleeding for the National Party, with Labour taking an even more commanding lead in the latest poll - less than two months out from the election.

The National Party has fallen to a low of 25.1 per cent in the first public poll since Collins took over as leader from Todd Muller on July 14. The party was on 30.6 per cent the last time the poll was conducted in May - a number that effectively ended Simon Bridges' tenure as leader.

Labour is now at 60.9 per cent (up 4.4 per cent - the highest it has been in the Newshub-Reid Research poll) and will be able to govern comfortably alone with 77 seats, according to the poll.

Asked by Hosking about her 40th birthday yesterday, Ardern said: "It was very quiet actually. I mostly spent the day with Clarke and Neve, which was really lovely, and then I read some Cabinet papers."

The Newshub poll of 1000 people, conducted between July 16-24, has a margin of error of 3.1 per cent.

ACT has overtaken New Zealand First for the first time in Newshub's poll - ACT is at 3.3 per cent up 1.5 points. NZ First is down 0.7 points to 2 per cent.

According to the poll results, the Greens would still make it into Parliament on 5.7 per cent. On these results the party would have seven seats in Parliament. If ACT leader David Seymour could retain the Epsom seat, ACT would have four MPs.

The poll comes after a tumultuous few weeks in New Zealand politics, which has been rocked by a series of scandals.

Labour minister Iain Lees-Galloway was sacked last week for an inappropriate relationship with a female staffer - days after National MP Andrew Falloon was sacked for sending a pornographic image to a teenager. Police are now investigating after it emerged he sent other images to at least five women.

The last Newshub-Reid Research poll in May signalled the end of Bridges, who was rolled by Muller shortly after.

Muller resigned after fallout from his handling of the Hamish Walker Covid-19 patient leak scandal.

Walker has also resigned after admitting leaking the information to journalists.

In May, the National Party plummeted to 30 per cent in the first public poll since the Covid-19 crisis took hold.

The poll had National at 30.6 - while Labour rocketed up to 56.5 per cent under Ardern's leadership through the Covid-19 crisis.

As preferred PM, Ardern was then at 59.5 per cent - up 20.8 points on the last poll and the highest any Prime Minister has scored in the poll's history.

National's worst ever election result was in 2002 when then leader Bill English led the party to 20.93 per cent of the vote.