National leader Todd Muller is accusing embattled MP Hamish Walker of going behind his back, and insists the National Party does not have a history of engaging in dirty politics.
Walker, MP for Clutha-Southland, announced on Wednesday he will not stand in the September election after admitting to passing confidential COVID-19 patient details to the press.
Muller told reporters on Wednesday Walker worked hard for his community over the last three years as an MP but ultimately made an error of judgement which has cost him his career.
"There is a human element to this that we must not forget at these times - that this a man who has given his all for his community and will be feeling very, very challenged and disappointed. But it's the right decision and I acknowledge that."
Shortly after Walker's revelation on Tuesday, ex-National Party president Michelle Boag confessed to passing on the data to him - information she said was made available to her as acting CEO of the Auckland Rescue Helicopter Trust (ARHT).
But ARHT said in a statement Boag has never had access to any clinical or patient data. Boag has resigned from that role and stepped down from Auckland Central MP Nikki Kaye's campaign committee.
Muller said he found out about Walker's involvement in the leaked data on Monday at which time Health Minister Chris Hipkins had announced an inquiry.
Hipkins told reporters on Tuesday the leak had a "ring of dirty politics to it".
"That's simply not true," Muller said. "This is an isolated incident and you've got to see it through that lens and I have acted very swiftly and we've got the right outcome... Hamish Walker went behind my back and made his own judgement."
Hipkins on Monday appointed Michael Heron QC to lead an investigation into the leaked information and Prime Minister Jacinda Ardern told reporters on Wednesday the probe will continue despite Walker and Boag coming forward.
"We need to assure ourselves that the personal and private information of New Zealanders is being appropriately shared even when it's for health purposes. I do think we need to give ourselves those assurances that who received that information were the right people.
"What we have an example of here, though, is someone who for political reasons used people's personal information as a weapon. That is never acceptable in New Zealand; in fact, my view is this is a wake-up call."
Muller said Walker is responsible for his actions.
"His judgement was fundamentally flawed and I'm on record a number of times now confirming that and he's paid the ultimate price of doing that."
National Party president Peter Goodfellow said a selection process will begin immediately to find a new candidate for the Southland electorate.
Walker will remain an MP until the election. Muller has stripped him off his portfolios.
The controversy is Walker's second rebuke from Muller.
Earlier this months he expressed "disappointment" in Walker for releasing a media statement warning thousands from "India, Pakistan and Korea" could be destined for managed isolation facilities in the south without consultation.
The minister in charge of managed isolation facilities, Megan Woods, described the press release as "racist" while the Prime Minister said she found the MP's comments "inappropriate".
Muller said Walker did not get the press release signed off beforehand.
"He didn't give it to us. He sent it himself."
Muller said the National Party has not lost credibility to criticise the Government.
"Not at all. The Government continues to demonstrate by the day the fact that their border management is still not at the expectations that New Zealanders have in terms of keeping us safe."
The Government announced on Wednesday that a man who arrived in New Zealand from New Delhi last Friday had briefly absconded from the Stamford Plaza managed isolation facility in Auckland on Tuesday evening.
It's the second time in the space of a week someone has escaped the facilities.