The Greens this year opened the door to the possibility of a formal relationship with National.
But fronting the campaign opening in Wellington, Malcolm savaged Mr Key's performance.
National had demonstrated "a disregard for the 200,000 children living below the international poverty line", a "clear lack of understanding on how to support children's education", and a "dispassionate and punitive approach to those in our prisons," she said.
The Prime Minister and his party had "an inability to follow through on promises of any kind ... and now a determination to sell a percentage of our strong revenue returning assets".
But National would "make anything up for a Hollywood mogul should they happen to come down this way" - a reference to employment law changes made in response to Sir Peter Jackson's warnings his Hobbit films would not be made here.
New Zealand was "fast becoming one of the most inegalitarian and backward countries in the OECD" but "we have a leader who seems to be more interested in talking about his cats on the radio, being seen at the rugby and getting on the cover of the Women's Weekly".
"I thought that was my job," said Malcolm, who last year was at the forefront of opposition to National's plans to open conservation land to mining.
Backing the Greens' policies, she said Mr Key's faith in free markets "no longer works, it's outdated and old fashioned".
Her broadside was followed by speeches from co-leaders Russel Norman and Metiria Turei in which they underlined their "kids, rivers, jobs" election policies and their confidence in achieving unprecedented gains on November 26.
Dr Norman also announced the Greens' savings policy which he said would increase retirement nest eggs by allowing those in KiwiSaver to have their contributions managed by the guardians of the New Zealand Superannuation Fund - a fee-slashing policy it says will increase the average nest-egg by up to $140,000.
While KiwiSaver was a good policy, Dr Norman said that like New Zealand's banking, it was dominated by foreign companies, many of which charged high fees for handling savings.
"We need to avoid the pitfalls of the banking sector, where a small number of Australian banks drove out competition and drove up fees."
The Greens' policy picked up on a Government savings working group recommendation.
"The Greens will do for KiwiSaver what KiwiBank did for the banking sector," Dr Norman said.
Dr Norman told the audience of about 300 Green supporters, candidates and MPs the party was part of an increasingly powerful global green movement, and was poised to make history by capturing at least 10 per cent of the party vote.
Mrs Turei said additional Green MPs would strengthen the party's hand, no matter who won the election.
"Let's be clear, more Green votes mean more gains, no matter what the make-up of Parliament, no matter what the coalition, no matter what the confidence and supply agreements."
WHAT SHE SAID
"We have a leader who seems to be more interested in talking about his cats on the radio, being seen at the rugby and getting on the cover of the Woman's Weekly. I thought that was my job"
On Key and National:
"An unshakeable and abiding love of fossil fuels ... and an inability to follow through on promises of any kind, but will make anything up for a Hollywood mogul should they happen to come down this way."
