Prime Minister Helen Clark yesterday attacked National leader Don Brash as a "corrosive and cancerous" person and unfit to lead New Zealand - just moments after she condemned the use of personal attacks and extreme rhetoric.
She also called him divisive and polarising and invited the National Party caucus to get rid of him.
The description came as a shock because it seemed the political temperature had dropped since Sunday and Monday when a furious Helen Clark accused Dr Brash and National of spreading malicious rumours about her husband, Dr Peter Davis.
By Monday night she appeared to have calmed and then spent Tuesday in Tonga at the royal funeral.
But hostilities resumed yesterday when she was questioned about standards in politics and Cabinet minister Trevor Mallard. It was Mr Mallard who two weeks ago interjected in Parliament about Dr Brash and his then private affair with businesswoman Diane Foreman.
"Personal attacks formed no part of Labour's strategy," Helen Clark said on National Radio yesterday. "That is where Trevor Mallard was out of line.
"But I can't state too strongly that Labour regards Dr Brash as a corrosive and cancerous person within the New Zealand political system."
He had been prepared to divide New Zealand over race relations in 2004 and involved the extreme moral right in an election campaign.
She said those problems were on the mind of senior National MPs.
"They know he is not fit to be leader in New Zealand. The answer to that lies in their own hands."
Helen Clark's attack followed two days of regional visits for Dr Brash where he continued to accuse Labour of "corrupt" election spending on the party's $446,000 taxpayer-funded pledge card.
"Until the National Party stops using extreme rhetoric about Labour, it's going to be hard to raise the tone and I suggest they need to reciprocate by agreeing that the sort of extreme rhetoric they have been throwing around needs to stop," said Helen Clark.
Later she said the use of the word "corruption" against Labour was "intolerable and had no place in a Western democracy".
Mr Mallard has previously said his threat to reveal secret private lives of MPs was in response to the deep offence felt by his colleagues at being called "corrupt" by National over election spending.