Winston Peters' lawyer and the man behind the New Zealand First Foundation - Brian Henry - is threatening to sue National leader Simon Bridges and senior MP Nick Smith.
Newstalk ZB's political editor Barry Soper has seen emails sent to the National MPs today.
Henry's apparently lost a major contract with the United States as a result of claims by the MPs that there's been an electoral loan scam by the party.
He's inviting Bridges and Smith to either repeat their claims outside the House, where they're not covered by parliamentary privilege, or apologise.
If they do repeat their claims he's threatening to sue them for defamation and special damages of up to $30 million.
He's produced a spreadsheet showing one loan to the party from the foundation which was fully repaid.
Smith told Newstalk ZB he stood by his comments, but he wouldn't repeat them.
He said he wouldn't be worth a 30th of what the lawsuit threatens and he felt nervous considering his family responsibilities.
Speaking to media, Peters said he was not suing anybody – "at this point in time".
Pressed on why Henry had threatened to sue National, Peters directed all questions on the matter to Henry himself.
"But I'm not on trial in this case, I'm not suing anybody."
He said he is not the claimant in this instance.
Peters told reporters he had "no idea what [reporters] are talking about" when again pressed on the issue.
"You're asking me about an action, details of which I'm not privy to and I think you should ask the person bringing the action, not to come to someone who is not a source at all."
He revealed that the New Zealand First Foundation has volunteered written material to the Electoral Commission, offering a meeting about some of the issues raised in the media.
He also told media that he has learned that overnight, New Zealand First has had the biggest surge in volunteers and membership applications, since 1996.
"And I thank you all, my friends in the media for making that possible."
Read the letter below:
Pressed on the New Zealand First Foundation, Prime Minister Jacinda Ardern wouldn't comment – saying that it was "simply not a matter for me".
Asked about Henry threatening to sue Bridges and Smith, she said that was an issue for Henry himself.
"Any decision that a private citizen like that chooses to make in relation to a political party, that's for them. That's just simply not for me."
She said any other issues raised about the New Zealand First Foundation was a matter for the Electoral Commission.
That is the agency that upholds and determines whether or not the law is being applied correctly, she said.
Asked if she was worried if the allegations against NZ First and the foundation would ultimately end up hurting her, she said no.
She said that she had "of course had conversations with the Deputy Prime Minister over the issues that he's currently dealing with."
But she said, again, that those issues were best determined by the Electoral Commission.
At multiple times during her media stand up, Ardern said she was going to allow "natural justice" and for the Electoral Commission to form its own judgment, before she forms hers.
She would not say what she would do if NZ First were found to have broken electoral laws – "I don't want to get ahead of that, or making judgment until the Electoral Commission does its work".
NZ First's Shane Jones said the loans saga would be satisfactorily resolved by the Electoral Commission when it sits down for a cuppa with the party.
Jones said it was all a bit of a media fuss, but once the Commission looked at everything, it would be suitably resolved.
On Tuesday, Stuff reported that the NZ First Foundation appeared to have hidden political donations worth almost half a million dollars between April 2017 and March this year.
Many of these apparent donations to the foundation do not appear on the party's electoral returns.
The Electoral Commission is looking into the issue and Act Leader David Seymour said he was considering going to the Police over the issue.