The Maori Party's support for the proposed Kermadec ocean sanctuary is hanging in the balance, while Labour is urging the Government to put the legislation to create it on hold.
Te Ohu Kaimoana - the Maori Fisheries Trust - says the sanctuary will extinguish all iwi customary, commercial and non-commercial fishing rights in the huge ocean area north-east of New Zealand.
It's going to court to challenge that - a move supported by a number of prominent Maori leaders including Sir Tipene O'Regan, Dame Tariana Turia, Sir Mark Solomon and Hon Koro Wetere and Dame Iritana Tawhiwhirangi.
Maori Party co-leader Marama Fox says her party's backing for the bill to create the sanctuary isn't guaranteed.
While it supports Te Ohu Kaimoana's legal action, it also supports the ambitions of two other iwi, Ngati Kuri and Te Aupouri, who have interests in the area and want a spot on the proposed Kermadec governance board.
"We should have never been forced to choose sides. This is typical divide and conquer tactics," Ms Fox said.
The Maori Party supported the bill at its first reading, but did raise concerns about the potential encroachment on Treaty of Waitangi rights, something it has subsequently raised with Environment Minister Nick Smith.
Meanwhile, Labour wants Te Ohu Kaimoana's legal challenge resolved before the proposed legislation goes any further.
The party's Maori development spokesman Kelvin Davis said the decision to create the sanctuary was made with only a feeble attempt to consult Maori.
The government says Maori haven't fished in the proposed sanctuary area for more than a decade and their rights aren't being diminished and Prime Minister John Key said it was unlikely legislation would be put on hold while the court case plays out.
No date for the court hearing has been set.
The proposed sanctuary covers 620,000 square kilometres about 1000km north-east of New Zealand.
The bill to create it passed its first reading unanimously in February and has been sent to a select committee for public submissions.