Sidelined National MP Jami-Lee Ross has been identified as the person who leaked Simon Bridges' expenses - but the MP furiously denies the accusation.
National leader Bridges called a press conference for 1pm and told reporters an inquiry by PwC had concluded Ross was the person who leaked the information.
But Ross, who has taken medical leave from Parliament, had pre-empted Bridges' press conference, taking to Twitter minutes earlier to say that the leak would be pinned on him.
He is now threatening to go public about what he claims is "unlawful activity". He did not elaborate.
Bridges said he had spoken with Ross about his conduct, which showed a pattern of offending.
Bridges called this a "pattern of conduct".
"The report here, speaks for itself," he said.
Asked why he did not just sack Ross, Bridges said because it's about the National Party – that's why he said he is bringing it before caucus tomorrow.
The National caucus would now discuss Ross' future with the party tomorrow.
"Suspension is definitely an option," Bridges said.
Bridges said allegations made by Ross today on Twitter were wrong and he was "lashing out".
The National leader said: "The report states that the evidence identified points to Jami-Lee Ross as being the person who sent the anonymous text message.
"John Billington, QC, has independently assessed the investigation report. It is his opinion that on the balance of probabilities the evidence establishes that Jami-Lee Ross was the person who leaked the expenses and the sender of the text message.
"Earlier today I visited Jami-Lee Ross with Paula Bennett and explained to him the report and the opinion of Mr Billington and gave him an opportunity to respond. I was not satisfied with his explanation.
"Finally, you will recall Jami-Lee recently took leave from Parliament given personal health issues. This action today is completely separate. I did not know what the investigation report would contain when those matters were addressed in recent weeks.
"The step that I have taken today is not made lightly. I am balancing the health issues with the considerable public interest in the outcome of the investigation."
In its report, PwC said it had not identified the leaker of Bridges' expenses with certainty, but the evidence pointed to Ross.
"Mr Ross, therefore, may be the text message sender."
The report showed Ross had been in contact with a Radio NZ reporter, Parliament's Speaker Trevor Mallard and a police officer in his electorate - all on dates that matched with how the leak and its aftermath unfolded.
"With one exception, our examination did not identify any evidence to suggest that any National Party MP is the text message sender.
"The exception is Mr Ross...".
But the PwC report added: "The evidence is not conclusive."
Bridges insisted his leadership of the party was still strong, despite a leak by one of his own MPs to embarrass him.
He said he had the full confidence of caucus, saying what the report shows is that was the action of one single Member of Parliament.
"I can do no better than say that I accept the finding of the report," Bridges said.
Bridges again rejected claims there were inconsistencies in relation to donations to the National Party.
The leak inquiry
The National leader has previously said he did not believe Ross was the leaker and that he hoped to see him return to Parliament.
Bridges' travel and accommodation expenses for the June quarter were leaked to the media three days before they were publicly released on August 16.
National's deputy leader Paula Bennett has overseen the investigation, which was carried out by PwC.
Speaker Trevor Mallard commissioned his own secret inquiry into the leak of Simon Bridges' travel expenses after hearing that Bridges had been privately blaming the Speaker for the leak.
The inquiry by KPMG cleared him and Parliamentary Service staff who had access to the expenses document, according to a memo written by Parliamentary Service and released by Mallard.
It means there were two separate taxpayer-funded inquiries going on at the same time, one into the National Party MPs and staff, and one into Mallard and Parliamentary Service staff.
National commissioned the PwC inquiry after Mallard cancelled the official wider inquiry which was to have been conducted by former Solicitor-General Michael Heron QC.
Mallard cancelled the Heron inquiry after it was publicly revealed that he, Simon Bridges and MediaWorks had received a text from the leaker claiming to be a National MP, containing reference to matters relating to caucus meetings, and pleading for an inquiry not to be held on the grounds of mental health.
National MP Jami-Lee Ross went on leave a fortnight ago citing personal health issues, it was announced last week by Bridges and Bennett but Bridges said Ross was adamant he was not the leaker.
August 13 - MediaWorks publishes a story based on Simon Bridges' leaked expenses
August 15 – Speaker Mallard agrees to hold inquiry
August 16 – Bridges, Mallard and Newshub receive anonymous text message allegedly from National MP pleading for inquiry to be called off on mental health grounds.
August 17 - Bridges talks to mental health experts and tells police about text on advice.
August 19 – Police tell Bridges they have identified and contacted the texter (wont name them) and that the person is getting support.
August 23 - Mallard names Michael Heron, QC, to conduct inquiry
August 24 – RNZ reveals that texts were sent the previous week to Bridges and Mallard, Ardern and other comment publicly.
August 24 - Mallard cancels Heron inquiry.
August 28 – On Mallard's request. Parliamentary Service starts an investigation into himself and PS staff who access to the travel expenses, using KPMG.
September 4 - Parliamentary Service reports that KPMG finds no evidence of any disclosure of the information to unauthorised parties.