'Smell of death' following Simon Bridges - Chris Trotter

There is a "smell of death" around Simon Bridges' leadership of the National Party, according to a leading political commentator.

Mr Bridges has had a tough week, with more leaks from his party making headlines and his curious use of the word "embarrassing" to describe the health issues faced by Botany MP Jami-Lee Ross.

A new email leaked to Newshub show the investigation into who leaked Mr Bridges' travel expenses has widened to non-Parliamentary staff. It's already covering MPs' communications as far back as February.

"This has got the smell of death about it," left-leaning commentator Chris Trotter told The AM Show on Thursday.

"When you see politicians gripped by this kind of paranoia, you know that things are very bad inside their party because why else would they be looking over their shoulder all the time?"

The expenses were leaked to Newshub only days before they were about to be made public. Speaker Trevor Mallard quickly cancelled a parliamentary inquiry, satisfied it was an internal matter for the National Party, which is paying for its own investigation using taxpayers' money.

Trish Sherson and Chris Trotter.
Trish Sherson and Chris Trotter. Photo credit: The AM Show

"They should never have had the investigation in the first place. These are figures that were going to be released anyway," said Mr Trotter.

"This is one of those rare moments when it's a cock-up and a conspiracy," added Trish Sherson, former ACT press secretary, wondering why the investigation will look as far back as February.

"Bridges handled it perfectly [on] day one. When those expenses were leaked he came out and said, 'Hey - I was doing my job.' It didn't seem to have anywhere to go, the story died pretty quickly, and then [came] the whole decision around going after who leaked it. That's just taken on a whole life of its own."

Mr Bridges told The AM Show in August it's important to find out who's behind the leak so "Members of Parliament to have a confidence about what happens with this sort of stuff" and "so the Opposition can do its job, so parliamentary democracy ultimately is safeguarded".

But Ms Sherson said there's no public good in finding out who leaked the expenses, and it's not a good look for National to be spending taxpayer money investigating the matter.

Mr Trotter said looking at communications as far back as February suggests the investigation is covering more ground that just who leaked the expenses, and that it's becoming clear National chose the wrong leader after Bill English stepped down.

"They have sent a boy to do a man's job... I cannot for the life of me understand why you would do this to yourself."

Spill on the cards?

Mr Trotter said Mr Bridges' days could be numbered, with hints of a plot to roll him forming behind the scenes.

"When you see pieces on the board moving about with this sort of speed, obviously there are things happening which we can't see but people are responding to moves other people are making. I cannot for the life of me understand why you would do this to yourself..."

Labour went through a series of leaders before finding the one who could take them to victory. Mr Trotter expects the same will happen to National.

"National is entering that terrible deadzone where all eyes are only on the leader - not on policy, not on the party, the deadzone that Labour lived in for nine long years."