Customs Minister Meka Whaitiri has announced she has quit Labour and will stand for Te Pāti Māori - a surprise move Labour says has not been explained.
She appears set to be automatically ejected from Parliament under the "waka jumping" legislation.
Whaitiri confirmed the move on Wednesday in an event at Waipatu marae in Hastings, saying the decision to cross the floor was not an easy one, but was the right one.
"This morning, I have officially notified the Speaker that I have resigned from the Labour Party and am joining Te Pāti Māori," she said.
Sepuloni confirmed Whaitiri has had her ministerial responsibilities removed.
"Prime Minister Chris Hipkins made the decision on confirmation of Meka Whaitiri's resignation from the Labour Party this morning," she said.
"As Acting Prime Minister, I have advised the administrator of the government to give effect to that decision this morning."
"Obviously we're disappointed in Meka Whaitiri's decision, but we are moving on," she told reporters.
"When you've had a colleague for this long, it's really hard to see that person go and it was very unexpected."
She said permanent allocation of Whaitiri's portfolios would be made in the next week. In the meantime, Kieran McAnulty would be acting Cyclone Recovery minister for Hawke's Bay, Ayesha Verrall would take over Food Safety, Peeni Henare would hold the Veterans portfolio, and Damien O'Connor would take Customs.
Whaitiri, in her speech at the marae, offered little explanation of her decision to quit Labour, referring instead to a commitment to Māori political activism.
"He Whakaputanga, Te Tiriti o Waitangi, Te Kotahitanga, Ngā Komiti Wāhine, Māori Council, Māori Women's welfare league, Congress, Hapu Authorities, marae, iwi chairs - the point here whānau is Māori political activism is part of being Māori. It comes from our whakapapa and we as Māori have a responsibility to it.
"Today I'm acknowledging that whakapapa, I'm acknowledging my responsibility to it and it's calling me home."
Tearing up, she delivered a message to the electorate: "To the voters of Ikaroa-Rāwhiti, I have served you tirelessly for the last 10 years. Let me continue to serve you."
She seemed confident of being returned to Parliament.
"As the Ikaroa-Rāwhiti sitting MP, I intend to be seated with Te Pāti Māori when we return to Parliament, joining an unapologetic Māori political movement to achieve what was promised to us 183 years ago sends a clear commitment to Māori voters across the country.
"Te Pāti Māori sees you, we hear you and we will serve you, and we will never ever take your vote for granted."
Speaking to reporters afterwards she offered hardly more insight to her decision.
"It's my calling. It's who I am as a Māori, proudly so. As a wahine Māori from a place that has born great leaders and particularly from a marae that has brought great leaders and actually gave raise to the very first Māori parliament, the Kotahitanga movement, so for me it's coming home.
"Today is about announcing me coming home and the reasons why I've done that."
Whaitiri plans to stand for Te Pāti Māori in the Ikaroa-Rāwhiti seat she has held for Labour since 2013. She commanded a comfortable margin in the last election and is expected to be able to win it again.
Whaitiri exit likely to invoke 'waka jumping' legislation
Whaitiri said her resignation was effective immediately.
It seems certain to trigger the Electoral (Integrity) Amendment Act, the so-called "waka jumping" legislation. This means she would be ejected from Parliament and her seat would become vacant because she is no longer a member of the political party for which she was elected.
The legislation automatically vacates the MP's seat if they deliver a signed, written notice to the Speaker resigning from the party they were elected for. The reasoning is this maintains the proportionality of representation in Parliament.
A by-election would normally be required but - because it is within six months of the election - a supermajority of three quarters of MPs could agree one should not be held. This means National would need to support the move to prevent a by-election.
This would also leave the Māori electorate of Ikaroa-Rāwhiti - which stretches from Wellington up the North Island's east coast to include Hawke's Bay and Gisborne - without its MP in the wake of Cyclone Gabrielle.
Sepuloni said McAnulty was well equipped to manage the cyclone response for Hawke's Bay.
"The message is that absolutely we are not going to let this distract us. We are focused on the weather event recovery for that region and that is what we need to be focused on."
Whaitiri said Te Pāti Māori wanted to ensure the needs of Hawke's Bay were taken care of.
"I actually think that people will see this decision for what it's worth and it is a big announcement, a big decision, but the people of Kahungunu - and we've seen it - this very marae, Te Aranga marae, Taihoa marae in Wairoa, all came to the fore during Cyclone Gabrielle. Who's their voice, you know?
"We've got a lot of maraes around Hawke's Bay suffering now. I can freely go to bat on their behalf, and they are part of the wider community.
"We also want to ensure that our policy, what I will be doing is to ensure all the needs of Hawke's Bay are taken. You can't do that when you're, when you're - when you're with another group."
Te Pāti Māori president John Tamihere said the party was working through the details and legalities with the Speaker of whether Whaitiri would remain an MP until the election, and it would be inappropriate to say more at this stage.
Sepuloni said the party had not seen the letter Whaitiri claimed to have sent, and whether she would be ejected under the legislation at this point was uncertain.
"We're not going to invoke, and so the other way is through the Speaker and that is up to Meka and the Speaker.
"We haven't seen a letter, we haven't received any evidence of a letter ... we don't want to overinterpret things right now because we haven't got all the answers.
"That's a hypothetical that we're not going to answer now. We need to see what rolls out over the course of the next day or two."
Davis said much the same.
"We're not going to speculate. She's moved on - we don't want to create bad blood with her," he said.
"We'll find a candidate to stand in Ikaroa-Rāwhiti and we'll set out to win it but we have to wait for the election to see what the outcome is."
Move took Labour by surprise
Sepuloni said the move had been a surprise for the party, and Whaitiri had not explained her decision.
"We haven't had a reason either. There was no contact made with the leadership, no explanation given to date. It really is Meka's decision."
Prime Minister Chris Hipkins said he first learned of the news after he landed in the United Kingdom as part of a trip to attend the coronation of King Charles III, and last spoke to her before the Easter recess.
He told reporters he had left her a message after hearing the news and "would expect if there was anything significant happening in that area that she would give me a call".
Whaitiri confirmed she had not informed her boss ahead of announcing her decision.
"He will have seen the announcement that I've made here on my marae in a tikanga Māori way, which was important to me as we moved into this amazing new opportunity for our people."
Sepuloni said she first heard a rumour about the move about midday yesterday, but at that point it had just been a rumour. She said when they found out about the possibility, senior Māori ministers spoke and decided Justice Minister Kiri Allan would go to speak with Whaitiri in person.
"We weren't able to reach her on the phone, and the feeling was kanohi ki te kanohi. Kiri was able to meet with Meka and the whānau this morning. I'm not going to disclose what their conversations were - that was a private meeting between them - but that is the contact that we've had."
Labour deputy leader Kelvin Davis said Whaitiri's exit was not something they want to see happen, but "the Labour caucus is keen to just get on and deal with the work".
"Up until yesterday, we believed that she was going to be standing for Labour. This is her decision, and like I say it's taken us all by surprise.
"Obviously we're disappointed and Meka was a member of the Māori caucus and the wider caucus but obviously she had her reasons."
'She's doing it for the mana of our people' - Te Pāti Māori president
Tamihere said Tariana Turia had crossed the floor taking a stand on a "catalyst issue", but Whaitiri "does a totally different kaupapa, she's coming home to her whakapapa".
He said it was no disrespect to Turia's defection to say Whaitiri's "takes courage, enormous courage for her to do this".
"She's walking away from a ministerial job, she's walking away from a sure thing, and she's walking into an unknown but she's doing it for the mana of our people and that is something special," he said.
"She's crossing the floor to cross the bridge to her own emancipation from being controlled by others to a party that she controls."
Heather Skipworth had been announced to run in the seat for Te Pāti Māori but she will now step aside.
Tamihere thanked Skipworth, saying it was "a big thing to put your ego and your mana to one side to awhi your cousin".
"I only wish some of our men could think that way."
Whaitiri thanked her too.
"Can I just add my mihi to my cousin Heather. Thank you for bringing us together and I can't say anything but I love you, I love your whānau, our whānau."
Te Pāti Māori co-leader Debbie Ngarewa-Packer said today was about "saying we've had enough".
She said the hardest thing in the last couple of days had been the decisions made "when we're advancing ourselves, when you are an aunty, a best friend, a nanny of a whānau, you're an aunty of a moko, and in amongst all that pain you're navigating your personal relationships versus what's right for the kaupapa.
"When do we have to stop fighting and compromising and giving and taking in this and losing friendships, loveships. Because the kaupapa calls us, and that's how I've arrived here today."
Co-leader Rawiri Waititi said the decision had liberated the seat for the people.
"What Meka has done is liberated Ikaroa-Rāwhiti from being a seat that's been locked to Labour since the 1940s, so this is an opportunity to bring the seat back to iwi Māori, to tangata whenua, to be the true voice of our people and not to be hamstrung by Pākehā parties and Pākehā agendas."
Whaitiri was reinstated as a minister outside Cabinet in 2020 and holds the Customs, Veterans, Food Safety and Hawke's Bay cyclone response portfolios.
She had been stripped of her portfolios in 2018 after allegations she bullied her press secretary, with a report finding it "more likely than not" she left bruises after grabbing her employee.