National leader Todd Muller says he believes his party has been "transparent" about the leak of Covid patient details.
And rejects it was a lie by omission that he didn't reveal Michael Woodhouse also was sent sensitive information by former party president Michelle Boag.
"From my perspective, we have been well-managed and transparent about it," Muller said.
Meanwhile, Woodhouse said he didn't say something sooner because he didn't think he had the same information as Hamish Walker, who admitted leaking details of 18 active Covid cases to media.
• Michelle Boag quits the National Party, sent Covid patient details to Nat MP Michael Woodhouse
• National MP Jian Yang to retire from politics following election
• National leader Todd Muller knew Michael Woodhouse was also sent Covid patient data
• National MP Hamish Walker who leaked private Covid info resigns
This morning, Woodhouse confessed publicly that he also received Covid patient data from Boag in four unsolicited emails between June 21 and 25.
Boag this morning quit the party saying the past few days "have underscored for me the unhealthy relationship I have developed with politics".
Woodhouse told the Herald that before sending the emails, Boag called him and said "she had some information around Covid that would be helpful to me" and sent it to a private email address.
He said he opened one of the emails but "and clearly there was nothing that I could benefit from and I did not use it".
On Saturday, the Herald broke news that details of 18 patients with Covid-19 had been leaked.
Woodhouse said he texted Boag to say: "I'm sure I don't have to say this but I am absolutely not the source of the leak.
"She contacted me to say, 'I know you're not the source of the leak because the information is different' and that was the end of it as far as I was concerned until Tuesday evening."
Woodhouse said it "never crossed my mind" Boag was behind the leak as he understood the information was circulated widely around health agencies.
Also on Saturday, Woodhouse said about the leak: "This is unconscionable and unacceptable that those suffering from the incredibly dangerous virus now have to suffer further with their private details being leaked."
On Monday the Government announced an inquiry headed by former solicitor-general Michael Heron, QC, into the source of the leak.
On Tuesday evening National's Clutha-Southland MP Hamish Walker admitted he was responsible and Boag confessed to being his source.
Woodhouse said after that happened, he gave Muller "a quick call to say I think there could be another dimension to this story. He asked me to talk to Amy Adams in the morning about that, which I did".
He deleted the emails that evening.
"I'm still not sure the degree to which the two stories are connected because I don't know [the media has been leaked] and I frankly don't have a lot of information about what I had because I didn't look at it that closely."
On Thursday, Muller was asked in a press conference whether he'd checked if Woodhouse had received the same information Boag had sent Walker.
Muller said: "No. It's very clear from our perspective that there is a conversation that's occurred or a connection that's occurred between Michelle Boag and Hamish Walker."
He said it wasn't accurate to say he didn't know whether other MPs in National had access to that information.
"We are confident from what we can see that the issue here relates to Michelle Boag and Hamish Walker ...You've heard very clearly from the participants that the issue was between Michelle Boag and Hamish Walker."
Muller said today he was focused on "the issue relating Hamish Walker" because the question was put in that context.
"The information that was leaked - that information was different to what Michael had received and Hamish received it and leaked it.
"And from my perspective what Hamish did was unacceptable and that is well-canvassed. When I got that question I was looking at it through the lens of the information that Hamish received.
"Look to be clear, I could have put it clearer but that was the distinction in my mind when the reporter asked that question."
Asked whether that was a lie by omission, Muller said: "I reject that premise. I was the one that made sure that we made this public on Tuesday ... actually, from my perspective, we have been well-managed and transparent about it.
"I've shared from my perspective what's appropriate so I reject that."
Muller was asked if Woodhouse should have reported that he'd received such sensitive information and that was "a lesson from this".
"The critical thing here is Hamish Walker received information and then leaked it and that is the lack of judgment and serious misjudgment and error that has cost him his career.
"From my perspective what was important was two things, that one, when I got told it and got clear the next day the scale of information that he'd received earlier.
"I made it very clear that we should circle back to Michael Heron if it was any way relevant to his inquiry and we've made it clear today."
Whether Woodhouse receiving that information, not reporting or deleting it until Tuesday night and that he assured Boag he hadn't leaked it to media called into question his judgment.
"No, from my perspective, the poor judgment, in my view, is the judgment of taking sensitive information and releasing it because MPs receive information all the time, and you would understand that."
The Herald pointed out that it reported the information the day after receiving it.
"From my perspective I have reinforced that message to my caucus."
Muller said: "The critical error of misjudgment was Hamish Walker in terms of leaking that information."
Muller said he was disappointed Woodhouse hadn't told him sooner "but it needs to be put in the context that he obviously didn't do anything with it".
He said he stood by Woodhouse "one hundred per cent".
Muller has not asked all his MPs whether they'd also received sensitive information from Boag.
He said he'd "reinforced" to his caucus his expectations of them and that if they receive highly sensitive information like that, they should elevate it to the leadership.
Muller said he didn't think the latest developments "will be huge at all" for the National Party.
"I've for one have of course made sure that this made public, it's cost an MP his career, the former party president her involvement with the National Party and I've been very clear in terms of expectation of behaviour and how we deal with sensitive information in the future."
Muller said Boag's decision to resign from the National Party was the right decision but would have been "very hard" given she'd spent her whole life supporting the party.
National deputy leader Nikki Kaye said she had not received any confidential information from Boag, but they were friends and she had spoken to her this morning.
"I'm very sad about the situation. I have spoken to her. I think it's very gutting and a disappointing situation and Michelle's taken responsibility for her mistakes.
"She is someone in my view who has contributed significantly both in charitable work but also for many, many hours for the National Party, so I think it's a very sad situation."
Kaye was part of the team that discussed what to do after Woodhouse revealed the emails from Boag to Muller on Tuesday night.
Asked if the party should have front-footed that information yesterday, she said: "I think it's really important to work through a process and understanding what the information was was part of that."
She said Woodhouse went to Heron, who is conducting an inquiry into the privacy breach, within a "reasonable timeframe".
"People will have a view on that but I think what's important is that that was disclosed to Michael Heron, and then obviously confirmed publicly."