The National Party under Simon Bridges has just 29 percent support according to the latest poll from TVNZ.
The figure is a 17 percent fall for the opposition party from the previous 1 News Colmar Brunton Poll, and is the lowest for National since 2003.
Labour was up 18 percent on the previous 1News poll to 59 percent, the best result for that party in the history of the poll.
"This is as bad as it's been since 2003 I think," political commentator David Cormack said.
He told Checkpoint with the latest poll numbers, he believes Judith Collins will swing in behind Todd Muller.
Former National and NZ First MP Tau Henare told Checkpoint he thinks Simon Bridges will be gone at the September election if not before.
"If I was him I'd walk away now," Tau Henare said.
He said the polls have not only been about Ardern's prominence through the Covid-19 response.
"It's been about Simon and the way he's handled it since he became leader, and it's been going down every time," Henare said.
"It's not only bad for Simon but it's bad for the party. What's worse for the party is that a couple of months out from an election they're having a leadership debate, a leadership challenge, which we thought only happened in Labour.
"This will devastate National like most of them haven't seen before."
Cormack said the situation is different to 2017 when then-Labour leader Andrew Little stepped aside for Jacinda Ardern, but remained a high-ranking MP in Labour.
"I think Andrew was a man of dignity & Simon hasn't really shown that… I think he's more inclined to take a 'burn it all down' approach. He already threatened the caucus earlier that if they rolled him he'd trigger a by-election, but I think he wildly overestimated his importance to Tauranga. I think National could run a donkey in that electorate and still probably win it," Cormack said.
Henare said National's situation is "nastier" than the spill he saw when Jenny Shipley rolled Jim Bolger.
"National are not going to win this election," he said.
"Todd's not an inspiring guy, I don't think he's going to inspire Mullermania the way we saw Jacindamania. It's still a chance, but I'd say at this stage, Simon, he's buggered," Cormack said.
