Wood's exit shows 'Chris Hipkins is weak' - Luxon

National Party leader Christopher Luxon says Michael Wood's behaviour shows prime minister Chris Hipkins is weak and failed to manage his team's culture.

Hipkins on Wednesday afternoon announced Wood had resigned all his portfolios after it was discovered he had a trust with further undisclosed shares that would raise concerns about conflict of interest.

Wood had been stood down as transport minister earlier in the month over a failure to disclose or sell shares in Auckland Airport over more than two years.

Speaking to reporters before heading into the debating chamber on Wednesday afternoon, Luxon said it showed failures by Hipkins.

"He's not building a strong culture, he's not setting clear expectations, and certainly his ministers aren't listening to him," he said. "The bottom line is Chris Hipkins is weak, he hasn't managed his team and he hasn't managed the culture inside it."

"When we go into government on October 14th I'll be crystal clear with all of my team on the culture and the expectations that I expect from them to manage conflicts of interest. But under Chris Hipkins in five months we've had a litany of failure in terms of ministers not understanding the cabinet manual, not understanding their obligations, and not showing high integrity."

"This is a government falling apart, the wheels are coming off, there's integrity issues and personnel issues every single week and New Zealanders are over it.

Hipkins also announced five changes to tighten the requirements for ministers to disclose potential conflicts of interest.

He had also sought advice on bringing in additional rules similar to Australia's which would mean ministers could no longer own shares unless it was public superannuation funds or an arrangement where the minister had no control or visibility over investment decisions.

Luxon said the changes all seemed quite reasonable.

"I would have thought it was already in place, I would have thought Chris Hipkins would already have put it in place. All of that seems quite reasonable and I'm up for considering it all."

He said he would be ready if Hipkins called a snap election.

"I'm ready to go, I'll go any day, I'll go tomorrow. He's not doing the job and I'll do the job for him, I'm very happy to do that."

ACT's David Seymour also supported Hipkins' actions.

"It's absolutely mind-boggling someone could have so many blatant conflicts for so long and do so little about it. It's good that he's gone because if decision-makers have a vested interest in the decision they're making it undermines all New Zealanders' trust in public officials.

"I'm genuinely flummoxed because I've known Michael for almost 10 years, I think he's a decent and diligent person, I just can't understand how he could be so reckless. I wish him well, I guess he could have a pretty good future as a stock broker."

But he did not give up the chance to attack the government.

"This is not just a he-said-she-said-Parliament issue. If you wonder why the roads are c**p, immigration is c**p, it's because look who's been in charge of it all this time."

Deputy Prime Minister Carmel Sepuloni will take over the workplace relations and safety, and minister for Auckland portfolios. She said she was disappointed.

"We're all feeling that way. I've worked with Michael for a long time, he's been a very good minister and for whatever reason he's made these mistakes and he accepts that it's untenable to continue.

"It is hard to understand how someone so capable, so competent, who's always demonstrated the highest level of ethical behaviour that they could end up in this situation. It is confusing."

She said as an Auckland MP she already spent a lot of time there and had worked with Wood during and after the Anniversary Weekend floods. She would wait to receive briefings on workplace relations before commenting, but would "continue the good work that Michael has done".

Other recent cases of ministers falling short of expectations - like Stuart Nash, and Kiri Allan - did not show a pattern of behaviour from Labour MPs, she said.

"They're all very different in lots of ways, it's a few very unfortunate scenarios that have unfolded, it's certainly not a pattern of behaviour for our Cabinet ministers.

"You don't want the public to have this perception of politicians, it doesn't necessarily just taint one party often it has an impact on the perception of politicians across the board, and that's disappointing."

Andrew Little will be taking over the immigration portfolio and said he was very much looking forward to it.

"As you know I'm a glutton for punishment and tough work ... there's always another hour in the day somewhere," he said.

He rejected the suggestion the wheels were coming off the government.

"No. Look, it's very unfortunate what's happened with Michael but we've had a big work programme to do. We're now four months or so out from the election, we're now focused on the election as opposed to more reforms, new policy.

"This is a government that has taken on some of the hardest issues - some foreseeable, some not - and we've done some incredible things that some people said we couldn't do. We've done it and we're going to the election very confident."

"I can't account for what individual ministers have done but prime minister Hipkins does an outstanding job in keeping the Cabinet focused, on the target, he's made some pretty hard decisions pretty much in the first weekend he was on the job, getting this government focused on what is needed."

He said with Wood remaining for now as an MP, "Michael will still be around, he's a good friend".

Seymour noted that - with just over 100 days before the election - voters would soon have an opportunity to vote in someone else.