A top Tainui leader is resigning to stand for the Māori Party against Labour's long-serving Hauraki-Waikato MP, who is also his cousin.
Rahui Papa has announced he will run against Nanaia Mahuta, who has held the seat since 1999.
She won it with a majority of nearly 8000 at the last election.
Mr Papa was until yesterday the chairman of Waikato-Tainui's executive arm, Te Arataura, which manages the iwi's business and land interests.
Last year, the Māori king Tuheitia broke with tradition and endorsed the Māori Party, and in March he said he'd support Mr Papa's nomination.