The prime minister may be forced to confront Maori Council leader Maanu Paul at Waitangi on Tuesday.
The Government has so far refused to speak to the council over Maori freshwater claims, choosing to deal with claimants affected by the semi-privatisation of power companies.
But Mr Paul says the Waitangi marae trustees have honoured the council by asking him and co-chair, Sir Eddie Durie, to open a forum on Tuesday morning that John Key is expected to attend.
He says he will use the opportunity to tell Mr Key the ownership of water is the issue of the day for Maori and the Government cannot dodge it forever.
"The Government is bound by legislation and by court direction to act in good faith and with reasonableness to Maori. Saying to Maori they don't want to talk to you Maori is not being reasonable and is certainly not in good faith."
Mr Paul says the Maori Council is a statutory body and by refusing to speak to it the Government has insulted its mana.
Mr Key is defending his Government's record on Maori issues, as he prepares to visit Waitangi.
He says it's up to the Maori Council, whether it confronts him directly.
"Well, look they're free to go and do that of course. We'll have a number of meetings with iwi leaders and the likes.
"It's always a pretty full programme but ... I understand the Maori Council's perspective when it comes to water. We've seen those arguments now taken to the Supreme Court ... I stand by the views that I have always held."