The investigation into who leaked details of National Party leader Simon Bridges' expenses points to MP Jami-Lee Ross leaking the information.
Mr Bridges said the report pointed to Mr Ross as sending an anonymous text.
The PWC report said it had not identified the leaker with certainty, however, "the evidence we have points to Mr Ross".
As the National Party leader was about to make the announcement, Mr Ross posted a number of tweets in which he said he had fallen out with Mr Bridges some months ago.
Mr Ross said in his tweets that he had become "expendable" and that Mr Bridges was about to "pin his leak inquiry on me".
"He can not find who the actual leak is," Mr Ross wrote.
He claimed Mr Bridges was attempting to use contact with Mr Ross' local police area commander and a journalist he is friends with as evidence that he is "somehow involved".
"I have said they are unrelated - he does not wish to believe that. Some months ago I fell out with Simon. I have internally been questioning leadership decisions he was making, and his personal poll ratings which show he is becoming more and more unlikable in the public’s eyes."
Mr Ross then made an accusation saying he had recorded the National Party leader "discussing with me unlawful activity that he was involved in".
In his tweets Mr Ross added: "Working on his instruction, he asked me to do things with election donations that broke the law".
Mr Bridges denied all of Mr Ross' accusations and called Mr Ross' tweets "false comments".
"He would say those things, given the situation… I've released the report… and it speaks for itself."
Mr Bridges said suspension of Mr Ross from the National Party caucus was an option.
The inquiry came after the National Party leader's expenses were released earlier than scheduled, revealing $113,973 was spent on travel and accommodation between April and June.
Last week, an independent review found no evidence that staff in the office of Parliament's speaker, Speaker Trevor Mallard, or Parliamentary Service finance and corporate staff released details.
Earlier this month, Mr Ross took time off from Parliament for health reasons, with Mr Bridges saying it was unrelated to the leak inquiry.