The head of the largest iwi in the Te Tai Tonga electorate says although many Ngai Tahu people oppose the direction of the Maori Party, it will not try to influence votes.
There have been suggestions that the Maori Party's support of the Marine and Coastal Area Act will lose them the electorate, currently held by Rahui Katene.
The bill was passed into law on Thursday and was supported by the National Party, the Maori Party and United Future.
It repeals the Foreshore and Seabed Act 2004 and restores the right of Maori to seek customary title in the courts.
Ngai Tahu have been strong opponents of the legislation, saying that the threshold test for Maori proving they have customary title of the foreshore and seabed is too high.
The chairman of Te Runanga o Ngai Tahu, Mark Solomon, says many members are strongly opposed to the legislation, but the organisation is apolitical and will not tell its people how to vote.
Ms Katene does not believe she is losing much support. However, she has confirmed that the chairperson and secretary of Te Tai Tonga's Wellington branch have resigned over the Maori Party's support for the new legislation.
Matt McCarten - a supporter of MP Hone Harawira, who quit the Maori Party over his opposition to the legislation - believes the party is in big trouble.
But Ms Katene is confident she can win the Te Tai Tonga seat again, which covers the South Island and the Wellington region.
She admits the marine and coastal legislation has been a big risk for the Maori Party and says many people still do not understand the benefits of the law.
The MP says the new law needs to be tested and she will be actively talking to rununga about pursuing a case.