Greens co-leader James Shaw used his speech to party faithful at the party's annual conference to take aim at National and its leader Simon Bridges.
On numerous occasions, he referred to Bridges and his colleagues as the "new climate deniers" and accused the National leader of being desperate and dangerous.
He accused Bridges of using Trump-like tactics to spread "misinformation".
His speech came just hours after he told Newshub Nation that the Greens had ruled out any sort of coalition with National after the next election.
"I would never empower someone with as little personal integrity as Simon Bridges to become Prime Minister," he said.
But Bridges said Shaw's comments show that the "pressure is clearly getting to him".
Shaw also used the speech to unveil New Zealand's first cross-Government climate change action plan.
He said it would lead to fundamental changes to how Kiwis get around our cities, heat their homes, farm, and dispose of waste.
But the focus of Shaw's speech in Dunedin today seemed to be to criticise National – the "new climate deniers".
He said he criticised Bridges for saying that declaring a climate emergency was "nothing more than political posturing and virtue signalling".
He said National was driven by calculated, short-term self-interest because the party thinks it's good for its polling.
"I believe that the gravest danger we face right now is the narrative that's being spun by Simon Bridges."
That narrative, according to Shaw, is that climate change "is not a big deal" and that half a per cent more of economic growth is a more important concern than the impacts of climate change.
"That is the new climate denial: the denial that we need to change how we do things, to avoid a climate crisis – it is desperate and it is dangerous."
He said to say that there is not a climate crisis, as he suggested Bridges had done, was "at best uninformed and at worst misleading".
Shaw went as far as saying Bridges was spreading fear and misinformation when it came to the climate change debate, by highlighting how much money it might cost people to adapt to fight climate change.
"He figures it worked for Trump. It worked for Brexit. It worked in Australia. He figures it'll work here too."
Bridges said Shaw's comments show that all the new taxes being lumped on to Kiwis, alongside the failure to deliver some key election promises, was starting to concern New Zealanders.
"They are working out we can't afford this Government."
Shaw also today released the Government's response to the Productivity Commission's report, released a year ago, into how New Zealand could reduce greenhouse gasses.
The report contained 77 recommendations – Shaw said the Government is moving to implement or develop all but one of them.
Most of these recommendations are already being worked on as Government policy, or areas the Government has committed to addressing the future – such as getting more electric vehicles on Kiwi roads.