Protesters showed a united front at the Waitangi Treaty Grounds. Photo: RNZ / Peter de Graaf

Ngāpuhi leaders, the Kiingitanga, Rātana and iwi leaders from around the motu sat united to welcome the coalition government to Waitangi.

Alongside them were thousands of people, many with messages of protest. Some were kura kids. They arrived early, many bringing their own chairs and kai.

All wanted to be part of the discussions and challenges around what is being called a three-headed taniwha and its proposal to redefine the principles of the Treaty of Waitangi.

As the haka pōwhiri roared across the treaty ground on Monday, the public joined in.

It was always going to be a hard ask for the government leaders to win over the crowd, and they did not try to.

ACT leader David Seymour said he welcomed the debate, then doubled down on his speech, to the point where people started singing a waiata to stop him from speaking.

But he had a hard act to follow - a challenge from activist Hone Harawira, who took direct aim at the government's Treaty Principles Bill, to cheers from the crowd.

"You and your shitty ass Bill are going down the toilet. That shitty ass Bill is going down the toilet."

Harawira said he'd spoken about the fight for the Treaty for decades.

"Here we are today and you buggers want to get rid of it and you think it's just a case of bring in some legislation to strip the Treaty of its mana, to belittle the reo by making it a second-class language in our land. It ain't gonna happen.

"You need to know that. There's more important things to be doing if we are trying to build this nation than mucking around with the Treaty of Waitangi."

After Harawira finished his speech, a group of activists holding placards reading Toitū Te Tiriti (Uphold the Treaty) began a haka.

Annette Sykes of Te Arawa also called out Seymour for "tinkering with Te Tiriti" and presenting "rewritten lines in te reo Māori to the nation that don't make any sense".

"You're not off the hook, prime minister," she told Christopher Luxon.

"I actually have real respect for Winston. I think he only went in for power... But why would someone who wants to be the leader of a National party permit the tail to wag the dog ... Māori are 20 percent of the vote," she said.

"We demanded better care and we should have been talked to before you allowed the tail to wag the dog."

Ngāpuhi leader Mere Mangu spoke before Luxon and, in an impromptu display, she led the prime minister to the mahau of the whare rūnanga (the porch of the meeting house).

"He came here with a purpose and that purpose was to be heard by the people and so ours is to ensure that his voice is heard by the people. If the people decide otherwise, well, there are practices within the tikanga that allow them to express that," she said.

One of those practices was to begin a waiata before the speaker had finished their kōrero - something that happened to both David Seymour and fellow ACT MP Nicole McKee.

Mangu said that was tika, or correct, but shouting people down was not in accordance with tikanga.

Activist Eru Kapa-Kingi spoke briefly before the prime minister.

He said the government's kōrero was degrading to the tino rangatiratanga of te ao Māori.

Kapa-Kingi said opposition to the proposed Treaty Principles Bill was the main priority.

"Our capacity is long and wide," he said.

"As soon as that select committee process comes up, we'll be flooding that with well-written submissions, well-articulated because we know how this game works."