Political leaders are descending on Tūrangawaewae Marae in Ngāruawāhia - the heart of the Kīngitanga - for the first time since the coalition government was formed, but there is one notable absence.
Kīngi Tūheitia extended an invitation to this year's Koroneihana to politicians from across the political divide, bar ACT MPs, who said they had not been welcomed to attend on Monday afternoon.
A spokesperson for leader David Seymour told RNZ an invitation was received to attend the King's anniversary on Wednesday, but with the House sitting at Parliament this week, Seymour was unable to attend. However, he "wishes the King well", the spokesperson said.
An invitation letter sent to the ACT leader on 13 May refers to the Wednesday events but does not mention the Monday speeches at all.
However, the organisers of the week-long coronation celebration told RNZ the ACT party was invited to attend on both Monday and Wednesday, but those invitations were declined.
Both Seymour and his colleague, Children's Minister Karen Chhour, have faced intense scrutiny from iwi leaders in recent months over a raft of government policies being repealed or introduced.
Political leaders arrive in Ngāruawāhia for Koroneihana
The reintroduction of youth boot camps, the repeal of section 7AA of the Children's Act, the Treaty Principles Bill and proposed changes to Oranga Tamariki and the Marine Coastal Act have all generated pushback and protest at varying levels.
At the same time there has been praise for other initiatives, including structural changes to Te Arawhiti - the Office for Māori-Crown Relations - and the reintroduction of charter schools.
Crown-Maori Relations Minister Tama Potaka told RNZ last week that iwi leaders had welcomed clarity on the role of Te Arawhiti, while Māori-led organisations had made up some of the 78 applications received for charter schools, which Seymour is overseeing.
On Monday, representatives and spokespeople for King Tūheitia and the Kīngitanga are expected to speak first in their welcoming of politicians, at which point the paepae will open to MPs.
Nominated speakers will have an opportunity to acknowledge the 18th anniversary of Tūheitia's coronation and speak to some of the challenges facing Māori, while also listening to the words of those from the Kīngitanga .
The prime minister has his own reserved speaking slot, as does Opposition leader Chris Hipkins, but fluent reo speakers Potaka and senior Labour MP Peeni Henare are also expected to kōrero for National and Labour respectively.
Other National ministers attending are Finance Minister Nicola Willis, Justice Minister Paul Goldsmith, and Social Development Minister Louise Upston.
The entire Labour Party Māori caucus will attend alongside Hipkins.
Both New Zealand First leader Winston Peters and senior MP Shane Jones will be at Ngāruawāhia, and both are expected to address the Kīngitanga.
Te Pāti Māori MPs will also join their Parliament colleagues in being welcomed to the marae, and Takuta Ferris will speak on behalf of the party.
The Green Party caucus, except co-leader Marama Davidson who is on leave receiving cancer treatment, will be at Koroneihana.
Co-leader Chlöe Swarbrick and MP Teanau Tuiono will both speak on Monday afternoon.
The Governor-General, Dame Cindy Kiro, was also due to be welcomed on Monday but flight disruptions on Sunday meant she was no longer attending.
The political gathering in Waikato on Monday will be the second hosted by Tūheitia this year.
In January, he put out a call to New Zealanders from across the country to gather for a national hui, and about 10,000 accepted the invitation.
MPs from a range of political parties attended that meeting, including National's Tama Potaka and Dan Bidois.
However, neither Luxon nor Hipkins were there.
Some at the hui criticised their lack of attendance, while others felt it was right that they did not show up, as it was not about them.
Those spoken to by RNZ at the time said it was about having an opportunity to discuss frustrations and concerns free of the politicians.
Tuheitia extended the invite in December after iwi leaders highlighted the need for a unified response to coalition government policy impacting Māori and Te Tiriti o Waitangi.
In his address on 20 January, he told those gathered that the turnout of Māori and non-Māori at the hui sent a strong message that the government would not be able to ignore.