At least 10,000 people are expected for the Ratana 25th Celebrations this year, Ratana Church secretary Piriwiritua Rurawhe says.
Last year's were bigger, because the birthday of the founder of the church, Tahupotiki Wiremu Ratana, fell on a Sunday. January 25 is the focal day for celebrations, and this year it falls on a Wednesday.
Numbers might be smaller but the event is likely to be a bigger than usual this year for politics, because 2017 is an election year. The Ratana celebrations usually start the political year, with the parties taking it in turns to make their pitch to Maori.
This year all the parties will arrive together at 10am on January 24, Mr Rurawhe said. The Maori King, Tuheitia Paki, and paramount Tuwharetoa chief Sir Tumu Te Heuheu will have arrived and been welcomed the day before.
"The chiefs of Maoridom will be sitting on the marae to hear policy for the election."
Rangitikei District Council will also be welcomed on January 23.
Whanganui's new mayor, Hamish McDouall, is to be welcomed on January 22 at 2pm, with Whanganui iwi who have finished their annual Tira Hoe Waka canoe journey and members of Te Runanga o te Awa Tupua.
Mr McDouall has been at Ratana before, when he was an aspiring Labour Party MP.
The Ratana kapa haka group, Te Reanga Morehu o Ratana, will be welcoming all the groups and supporting the church tumuaki and executive. Its members are also practising hard for the national kapa haka competition in Hastings, from February 22-26.
The Ratana Church has been engaging with political parties in recent months. Mr Rurawhe said it had talked to the Labour Party about TW Ratana's 1932 petition to government, which asked for the Treaty of Waitangi to be entrenched in legislation "under the banner of brotherhood".
The church will be working with Labour on "some key projects" in the coming months, he said.
Members have also been talking with the Green Party, with Winstone Peters and New Zealand First and with Maori Party co-leader Te Ururoa Flavell.
But the celebrations aren't really about politics. They are a gathering of faithful to celebrate the founders' birth, and their focus is on youth.
Other activities during the four days include talent quests, entertainment and sport.