Maori Party co-leader Pita Sharples says Labour's threat to stand candidates in Maori seats is "tantamount to [the seats'] abolition."
Labour's leader David Shearer said last month he would gun for the electorates, exploiting ructions in the Maori Party.
Last night, in a "State of the Maori Nation" speech, Sharples slammed the move.
"We cannot take the seats for granted," he said.
"Consider the risk posed by Labour. Placing candidates in Maori seats that are subject to Pakeha leadership, to a Pakeha caucus, to a Pakeha kaupapa is tantamount to abolition.
"Remember the foreshore and seabed?"
At Ratana last month, Shearer indicated his party would set out to win back three Maori electorates in next year's election - including Te Tai Hauauru , where Maori Party co-leader Tariana Turia sits.
He said Sharples was "looking fragile" in Tamaki Makaurau and Labour might even have a shot in Te Tai Tokerau, seat of Mana Party leader Hone Harawira.
Sharples' speech last night was a rallying call.
He said the Maori Electoral Option was "one of the most significant political turning points of our time affecting the balance of power in this country".
The option, offered every five years, gives New Zealanders of Maori descent the opportunity to choose whether they want to be on the Maori or general electoral roll for the next two elections. It is also used to revise electorate boundaries.
"It has the potential to give birth to six new Maori electoral seats, 13 Maori seats in total, if all of our people enrolled on the Maori roll," Sharples said.
"We must seize this opportunity."
The Maori option "provides an opportunity for Maori to increase political leverage" he added.
The speech also addressed the upcoming constitutional review.
Sharples floated the idea of a Treaty senate or a permanent assembly of Maori iwi leaders in Parliament. He said Maori MP Te Ururoa Flavell wanted MPs be given the choice whether to swear allegiance to the Treaty.
Sharples also suggested a new public holiday - to celebrate the coming of the kumara.
Sharples defended his party's much-criticised confidence and supply agreement with National.
Representing the "independent Maori voice at Cabinet regardless of who is in Government" was a form of activism, he said.
However, the speech made no reference to in-fighting over leadership which has divided the Maori Party in recent weeks.
Turia has said she will stand down next year and wants Sharples to do the same. But Sharples has vowed to fight on, despite a stand-off with Flavell for the top job.