Te Ururoa Flavell will step down as co-leader immediately and end his political career after his Maori Party failed to wins any seats in Parliament in Saturday's election.
However, Mr Flavell was optimistic the party could rise again - and believe a term "in the wilderness'' could even help it by reminding Maori of the importance of having the party's voice in power.
The Maori Party lost its place in Parliament after Labour's Tamati Coffey beat Flavell in Waiariki - the party's only remaining electorate and its lifeline. That means Marama Fox will also not return.
Mr Flavell said he was yet to decide what he would do in the future, but would step down from the leadership and not stand again.
"For the party it's time to reassess about what we've done and where we're going into the future.''
He expected a vote on the leadership of the party in the next six to eight weeks under the party's Constitution "and I won't be putting my name up again''.
He believed the party could survive - it still had upcoming candidates in the wings, such as prominent Kaitaia doctor Lance O'Sullivan who plans to stand in 2020.
"I think we do have the leadership to come through - it just means some rethinking, some rejigging, and some reorganising to get us over the line.''
Mr Flavell believed wider Maoridom would also reflect on the result.
"Maybe it's good that we stay out of the road for three years because then people will know 'actually what we had in our hand is now gone'.
"Did we really want what the election has given us in terms of an outcome where we have no Maori Party, but we have Winston to call the shots and a Labour Party which looks like it may well be in opposition for the next three years?''
He said the involvement of New Zealand First in a government was a "scary'' prospect for Maori given its policy for a referendum on the Maori seats and its opposition to Maori wards, Whanau Ora and Treaty of Waitangi clauses in legislation.
He believed a binding referendum on the seats would put them at serious risk.
"That's really scary because that sort of stuff has been built up for years and we've been part of that promotion.''
Labour leader Jacinda Ardern has ruled out holding a referendum, but abolishing the seats used to be National Party policy. It had shelved that policy under its governing arrangements with the Maori Party, but Flavell was not optimistic it would remain shelved.
"You're talking about running the country. At the end of the day parties will do what they gotta do. But if he's still committed to those five key things that are the antithesis about what we've been about as a Maori party, then it's up to Labour or National to decide if they're going to stay with it or not.''
He hoped his fellow co-leader, Marama Fox, would stay on as co-leader. "She's a dynamic personality that brought something extra to the party.
"She's a huge loss to Parliament and I"m hugely disappointed I wasn't able to get her there, or myself.''
Flavell's loss comes despite a deal with Mana leader Hone Harawira for the two parties not to stand against each other.
Flavell said the party's association with National had likely harmed it although he had believed they were doing valuable work.
"But clearly there was some damage along the way, the collateral damage about leaving people behind. And I was one of the advocates around that and really pushed for social investment and Whanau Ora as a way of dealing with that. But the people have spoken and you've got to take what you get.''
