The National Party is boxing ahead with its own investigation into who leaked Simon Bridges' expenses to the media after Parliament's speaker put the kibosh on an official inquiry last week.
That led to Mr Mallard pulling the plug on the inquiry saying it was unlikely the text had been sent from anyone outside the National Party.
Shadow leader of the House Gerry Brownlee said the National Party needed to know who the leaker was and will push ahead with uncovering the person's identity, after Mr Mallard had washed his hands of an inquiry.
"Well, of course, we think he's obfuscated his role as Speaker, but he did so after the prime minister had declared it was a problem for the National Party.
"We will now obviously conduct an inquiry, because we need to know who that person is, to either stamp out a problem, or to in fact wrap around someone who has some serious issues,'' Mr Brownlee said.
On Thursday 16 August Mr Bridges and Mr Mallard received an anonymous text from the person who leaked the opposition leader's expenses, saying if the inquiry exposed them publicly it would push them over the edge and put their life at risk.
The leaker provided information and details from caucus meetings over a period of weeks in order to prove their identity as a National Party MP.
Mr Bridges met with police about the matter the next day and on Sunday 19 August they contacted him to say they knew who the person was but would not be revealing their identity.
The following morning Mr Bridges spoke to Morning Report's Susie Ferguson and when she asked what it said about the support for his leadership if the leaker was indeed a National Party MP. He said: "That is pathetic frankly, we haven't got to that point. Let's see what happens. I don't believe it is - I think we've got a government who is seeking to distract. But as I made quite clear to you, obviously, if that were the case we would have a stern way of dealing with this. That would include the full gamut of options."
Fast forward to last Thursday and the inquiry gained more traction when Mr Mallard announced the appointment of QC Michael Heron to lead it.
That night Mr Bridges declined to comment when RNZ approached him about the text he had received a week earlier. The story broke on RNZ last Friday morning.
Mr Bridges then fronted media in Wellington where he said he was balancing making sure the person who sent the text got help while also ensuring the integrity of Parliament was upheld.
It was during that press conference that Police Minister Stuart Nash learned of the full involvement of police in the matter.
Mr Nash's office has confirmed that neither the minister nor his office were aware police had played a role until RNZ broke the story.
Under the 'no surprises policy' ministers can be told information that they may end up being asked to respond to by the media.
However, in this case, police only contacted Mr Nash's office shortly before 7am - after the story broke - and did not provide any details of their involvement.
As for any inquiry, the National Party will now deal with it, and Mr Brownlee said there would be very little public comment about how they would go about it.
This article was originally published by RNZ.