National has kicked "lone wolf" Jami-Lee Ross out of the party for his "appalling behaviour" – and say they would welcome a police inquiry into "baseless" corruption allegations.

Leader Simon Bridges said the party wanted to draw a line under the leak episode and be a united caucus going forward.

Bridges said Ross was "lying, leaking" and "lashing out" – and has welcomed police investigating the rogue MP's claims about donations to National.

He rejected Ross calling him a "corrupt" politician who was not fit to be prime minister.

Ross' expulsion from the party is a moot point given he quit the National Party today and plans to contest a Botany byelection as an independent candidate.

But Bridges said 55 MPs voted today to expel Ross - dispelling his contention that other MPs were dissatisfied with Bridges' leadership.

"The 55 people who know about this the most and the best have decided this is the right thing to do. It's the strongest possible action the caucus can take, and it's because we are united."

Bridges said Ross's allegation of corruption involving donations to the party were "baseless".

"They are entirely false and I invite Jami-Lee Ross to take them to police."

He invited police to investigate the allegations and was confident they would find no wrongdoing.

"It has zero chance of success, because it is wrong."

Bridges wouldn't say if he knew the Chinese businessman Zhang Yikun and the $100,000 donation, as it was now up to police to investigate.

The National leader repeatedly declined to answer questions about specific electoral donations.

"This is a matter where Jami-Lee Ross has made baseless, false but serious allegations. He should take them to police... the outcome will be clear and that is I've done nothing wrong."

Bridges described Ross as a "lone wolf".

He did not want to elaborate on what he has previously said was a "pattern of behaviour" from Ross. "We've expelled him from caucus and I'm moving on."

He called Ross' behaviour "appalling".

Bridges would not address Ross' claim that internal polling had Bridges' favourability rating at -27.

He said he would not waste his time when asked about whether he would take legal action against Ross.

Explosive claims

Ross had lashed out at "corrupt" National leader Simon Bridges, saying he will complain to police about the handling of donations made to the party.

Ross told reporters he plans to lay a police complaint over Bridges' handling of donations - and says he will provide a recording of a conversation with the National leader to support his complaint.

He revealed he has quit the National Party and plans to stand as an independent candidate in a Botany byelection.

Ross has also revealed that he was accused by National of harassing four women: "I was asked for details. I was not given any."

Ross said his questions were not addressed, and a week later, he went on sick leave: "It was difficult to accept, and I had a mental breakdown."

He said he was also hurt that Bridges characterised his issues as "embarrassing".

Ross told reporters he had started to question Bridges' leadership soon after he became leader.

He also questioned the legality of some of Bridges' actions. He initially thought Bridges was prime minister material, but no longer thinks that. Ross said it was clear he has had a falling out with his leader.

"He now has a net negative favourability of -27 in internal polling... the New Zealand public are not stupid."

Donation allegations

Ross claimed that Bridges filed a false electoral return. He says Cathedral Club is a front for a friend of Bridges that he knows well.

"Filing a false return is a corrupt place. Falsifying the name of a donor to hide the identity is a corrupt practice," Ross alleged.

Bridges yesterday denied any wrongdoing involving donations to the party.

Ross said Bridges asked him to collect a $100,000 donation which was then split into smaller amounts to hide it.

Ross later asked Bridges about the donation, and recorded the conversation.

Ross said he will go to police tomorrow to lay a complaint and allow them to hear the phone conversation with Bridges.

He will also release photos of Bridges with the donor, a Chinese businessman, but he stressed that he did not think the businessman had done anything wrong.

He named the donor as Zhang Wiyun.

The donation that he alleges is corrupt is separate from the donations that were discussed in a TV interview yesterday, he said.

Ross said the donation was made in May/June and alleged that it was covered up under instructions from Bridges.

He alleged Todd McClay was also aware of the $100,000 donation, and National Party general manager Greg Hamilton also knew about it.

Ross said the PWC report into the leak of Bridges' travel expenses had used his conversations with local police against him. He said it was not unusual for MPs to talk with local police.

Ross said he asked to address the caucus before the report was released to media, but this was denied.

"The campaign to push me out did ramp up considerably three weeks ago," Ross said.

He said when he asked Bridges about the four women he was accused of harassing, he was told that 15 women could be found. "Simon and Paula were the judge, jury and executioners."

Plans to contest Botany byelection

Ross said he is now mentally well again.

"I can no longer serve in a political party lead by a corrupt politician."

Ross said he will resign his National Party membership and his Botany seat.

He said his contract is with the people of Botany. "I have fought for my community."

He planned to stand as an independent candidate in the Botany byelection.

"I'm confident I can run on a track record of 15 years."

Ross said he still believed in National Party values, despite his dramatic falling out with Bridges.

"New Zealand deserves better from the National Party... I'm not proud of not speaking out until now.

"I am sad to be departing, for now, a party that has many good people."

Ross said other National MPs were also concerned about Bridges' leadership - but they were too concerned and would rally behind the leader.

He would not name other National MP who he said had had conversations questioning Bridges' leadership. The fact that he did so and was part of the inner senior team had lead to his falling out with Bridges.

Ross said that Amy Adams, Judith Collins, and Mark Mitchell - who all stood in the leadership contest - were all more capable and honest leaders than Bridges.

But it was up to the caucus to choose a leader, and he is no longer part of the caucus.

Ross said he was devastated to be accused of harassing women. His world crashed down around him and he got help.

He said he was "ambushed" and was about to lose his career and reputation. He thought long and hard about it and then asked Bridges for more information, but Bridges told him he could find not just four women, but 15 women.

"I wanted to know what the allegations were, but was never given the opportunity."

"If something has happened, I would like to know so I can fix it... I still have not been told anything."

Continued denial of leak

Ross insisted he did not leak the travel expenses, but said he did leak the later text message about the leaker because he was "floored" by the lack of compassion from Bridges.

He hoped leaking the text message would trigger compassion from Bridges.

"I made a call. I thought trying to get it out publicly... would offer the person a reprieve."

Ross noted that he is addressing media while the National caucus was meeting, but what happened in that meeting no longer concerned him as he was leaving the party and stepping down from his Botany seat to force a byelection.

Ross times accusations while National can't respond

National MPs are now meeting behind closed doors to decide the fate of accused leaker Ross, with many angry at his "disloyal" and "delusional" behaviour.

Ross waited till the caucus meeting had started to announce his media conference via Twitter.

There are reports that Ross' webpage has been deleted from the National Party website.

The sidelined MP was yesterday fingered by a PwC inquiry as the person who leaked leader Simon Bridges' travel expenses.

But Ross is not going quietly, firing out several tweets yesterday denying being the leaker, accusing National of "unlawful" behaviour and claiming he had secretly recorded some conversations with Bridges before taking health leave from Parliament two weeks ago.

The National caucus is now meeting to decide what punishment to hand out to Ross, with suspension an option.

Ross said the senior leadership of the party was going to push him out of caucus anyway.

He said he was happy to speak out now and stand for Botany as an independent MP in a byelection.

National MPs savage 'rogue, disloyal' Ross

Earlier today National MPs arriving at Parliament were critical of Jami-Lee Ross' behaviour - and declared widespread support for Simon Bridges.

Senior National MP Judith Collins says Ross has displayed "delusional" behaviour - and she was "fast losing interest in him as an MP".

Collins had been a supporter and ally of Ross but today's comments reflect the fury National MPs have with their rogue colleague.

Collins told reporters on her way into Parliament she would have her say at caucus.

"The tweets yesterday and the admission of taping Simon Bridges as the leader obviously to use it against him at some stage was extraordinary and I have never in my mere 16 years in politics seen anything like it."

She described it as "delusional" behaviour, but she had never suspected it. "I was floored 
by it."

Collins said she was not surprised by the strength of feeling from her caucus colleagues.

"We have a very united caucus and people are floored by this behaviour.

"I'm fast losing interest in him as an MP."

Senior MP Amy Adams said she "absolutely" had confidence in Bridges. She called Ross' tweets "extraordinary", saying she'd never seen anything like it.

"I think Simon's done an excellent job and he's got my full support."

Adams said there were questions to be asked from the report and from Ross' tweets.

"I value loyalty incredibly highly and I think our caucus values loyalty incredibly highly and we take a very dim view, obviously, when loyalty isn't shown."

Adams said she had no idea whether what Ross had claimed was true but she said it would be "very concerning behaviour" if he had taped conversations with colleagues.

"The whole series of events of the last few days raises important questions that are concerning and as I said, certainly unprecedented in my time."

Mark Mitchell also said he backed Bridges, and agreed with him that Ross was "lashing out" in his tweets.

Mitchell wouldn't be drawn on Ross' future before caucus met.

He revealed that he called Ross when it emerged he was standing down for health reasons.

"I definitely gave him a call when he was stood down for health reasons to make sure he was OK and to make sure his family was OK. He said he was focused on his recovery," MItchell said.

"We should definitely be checking on his welfare and wellbeing because he's obviously fighting some health issues. So absolutely, we should remain focused on that.

"We also have to remain focused on the contents of the report and getting to caucus today and having a discussion around that."

Mitchell said Ross' tweets and recording Bridges were a clear attack on National's leader and were disloyal.

MP Alastair Scott said Ross would be gone if he had his way.

He didn't believe National would use the new waka-jumping law because they had voted against it.

Louise Upston said Bridges was not the subject of today's caucus meeting, but an "MP that's been going rogue".

She called Ross' tweets "absolutely shocking" and said he had to answer for his actions.

Todd McClay declined to speculate on what caucus might decide, saying that was a matter that would be discussed later this morning.

Asked whether he backed National leader Simon Bridges, McClay said: "Absolutely, 100 per cent. This is not a matter of leadership, its about one individual who has shown significant disloyalty to every caucus member."

McClay said Ross' tweets yesterday, denying the leak and threatening to expose "unlawful" behaviour within National, were inappropriate and incorrect.

McClay said the entire caucus was disappointed. "We've been working very hard over the past year. Again, this is about one person who has shown great disloyalty to caucus."

But he didn't believe Ross' actions had caused any damage to National.

Alfred Ngaro said he backed Bridges 100 per cent.

"Leadership is not about the chaos that confronts you, it's about what do you after that. And I think he's done the right thing."

Ngaro said Ross had been a good colleague and a good friend and he was surprised by his actions.

Melissa Lee said the caucus was united.

"We're a strong team and someone decided they're not part of the team."

Jonathan Young said Ross' behaviour was "very surprising", and there was strong support for Bridges.

MP Simon O'Connor declined to comment on his way in, saying they were matters for caucus to discuss.

"The caucus is quite united in the job that we have, which is holding the Government to account.

"It's disappointing that one person has let the caucus down."

Scott Simpson said he backed Bridges but he didn't know whether Ross would remain in the party.

"I do have a firm view and I'm happy to say that in caucus"

Simpson called Ross' tweets "reprehensible".

MP Chris Bishop said it was "gut-wrenching" that a member of the team had done what Ross did.

"Up until yesterday he was a member of the team and he's made it pretty clear from his actions yesterday with the tweets just before Simon's press conference that he's not acting like a member of the team," he said.

"Disunity in political parties is not a good thing as you know."

Michael Woodhouse said he was right behind Bridges, and called Ross' behaviour "highly disappointing".

He would wait to see what Ross had to say - if he turned up to caucus today - but said disloyal was an apt description.

Andrew Bayly declined to say how he might vote but said he fully supported Bridges.

"It's a test of how good teams are and I believe we'll show we will be an excellent, resolute team, fully united and know where we're going forward."

Matt King called the leak saga a "hump in the road" and caucus would deal with it.

"For us as caucus we're tight, we're unified, we'll get on with it. This is bigger than one man."

King said he was "disappointed with the whole thing".

MP Stuart Smith declined to comment on Ross but gave his support to Bridges.

Ian McKelvie said he didn't come into Parliament to deal with such "unfortunate sideshows". He didn't think it had affected Bridges' leadership at all.

Nikki Wagner called it a "blip" in the history of a strong party but offered no other comment.

Process to suspend an MP

Otago University Law Professor Andrew Geddis told Radio NZ today that the National Party's constitution contained no provision for suspension or expulsion from caucus - and that may come down to a simple majority vote on a motion.

But the constitution did contain provision for disciplinary proceedings such as revoking party membership.

"Those would govern that procedure," Geddis said.

But that was legally contestable. "If the party moves to expel you and you don't think it has grounds to do so or you think it's not following its own rules, you could go to court and challenge the party's proceedings there."

Geddis said if Ross went to the Speaker and said he wanted to be an independent MP, his seat in Parliament would automatically become vacant and there would be a byelection.

If Ross was thrown out of caucus, Bridges could invoke the party-hopping legislation and go to the Speaker and say Ross was distorting the proportionality of Parliament and ask to have the seat declared vacant.

Boag: Bridges will come out of this stronger

Former National Party president Michelle Boag told MediaWorks this morning that Ross was acting alone.

"I predict that today, Simon Bridges will emerge from the National Party caucus with the unanimous support of every other MP. Actually, I think this has been good for his leadership.

"I was one of those who thought there shouldn't be an inquiry because it dragged it on. Now I'm very glad there was," Boag said.

She called Ross' actions "very irrational".

"The people I feel for are his family. I feel terrible for his family because they get dragged into this, and the people who worked with him very closely in his electorate."

Boag said there would be no way back for Ross in the way Maurice Williamson had done following a similar issue years before. "I predict that Bridges will come out of this stronger than when he went in."

"Now we know what the problem is, everyone else will come in behind. Everyone else will be united," she said.

Boag said if Ross had any evidence of wrongdoing on the part of Bridges, he should go to police.

Ross 'burnt toast'

Former National Party press secretary Ben Thomas told Newstalk ZB's Mike Hosking he has no doubt about Ross's fate.

"Jami-Lee Ross is burnt toast. He is probably on a five or six setting toast, that someone has forgotten about, that is smoking in the kitchen."

Thomas said Ross' tweets have alienated him from any sympathy from the wider caucus.

"This isn't going to be a referendum on Simon Bridges. This is just going to be about Jami-Lee Ross' conduct."

Thomas said National could invoke the waka-jumping legislation to get rid of Ross.

"I don't think National will have too many qualms about using it to cut out a problem."

An investigation found Jami-Lee Ross was the leaker, however, Thomas said there should never have been an inquiry.

"Probability suggested it was always somebody within the National Party camp, and it is fair to say it has probably been mishandled at every turn."

Former Labour Party president Mike Williams agreed, telling Hosking the situation was out of control.

"This matter should never have been pursued in the first place but I think Simon Bridges needs to be very careful because you will always have, in a caucus of that size, someone going off the rails."

Bridges needed to sort it as quickly as possible, he said.

"You can't welcome him back ... after what he said. If you expel him, you risk a byelection because of the waka-jumping Bill. There's no good answer."

Ardern: 'Pretty tough' for National leader

Prime Minister Jacinda Ardern told Newstalk ZB's Mike Hosking that the situation for Bridges was "pretty tough".

When asked to assess how Bridges had handled the fallout of the investigation Ardern said she would not "sit here and rank performance".

She commented that the Labour Party had gone through its own issues during its time in opposition.