It's impossible for Jami-Lee Ross to stay on in the National Party after an investigation found "the evidence we have points to" Mr Ross as the leaker of leader Simon Bridges' travel expenses, says 1 NEWS political editor Jessica Mutch McKay.
Mr Bridges today told a news conference, "The evidence establishes that Jami-Lee Ross was the person who leaked the expenses and the sender of the text message."
In a bid to trump his leader, six minutes before Mr Bridges was set to make the announcement, Mr Ross took to Twitter.
"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 unlikeable in the public's eyes," Mr Ross wrote."
1 NEWS political editor Jessica Mutch McKay says it's "impossible" for Mr Ross to stay on in the party.
"And now we've got a long drawn out, and embarrassing process for Simon Bridges to try to get rid of him," she said.
Mutch McKay says it raises questions about "the dynamics inside the National Party" and about "whether Simon Bridges' leadership is really so secure".
"Typically these kind of leaks come from opposing political parties. This has come form one of his own - a former close ally," Our political editor said.
Now National's caucus will decide Mr Ross' fate when it meets at Parliament tomorrow.
"Suspension is definitely on the cards tomorrow," Mr Bridges said.
It's then up to the party to expel Mr Ross, who's still the MP for Botany.
He can put up a fight and stay on as an independent MP, or resign from Parliament and force a messy by-election.