Acting Prime Minister and New Zealand First leader Winston Peters is calling for a two-pronged referendum on whether Māori seats should be entrenched, or should go altogether.
Labour MP Rino Tirikatene's member's bill to entrench the seven Māori seats was pulled from the members' ballot in May and will soon have its first reading in Parliament.
New Zealand First campaigned on holding a binding referendum on whether to abolish the seats.
At the time as Labour leader Jacinda Ardern ruled out a referendum, saying that would break faith with Māori voters.
Mr Peters said he still believed the matter should be put to the public.
"If you want to make changes to the electoral system, you should go to the country, not just do it unilaterally," he said.
Under Mr Tirikatene's bill, Māori seats would have the same protections as general electorate seats, meaning at least 75 percent of MPs would have to vote to get rid of them.
Mr Peters questioned the effectiveness of the protection proposed in the member's bill.
"The entrenchment to 75 percent looks good, until you can remove the entrenchment provision with an appeal and you're back to 50 again," he said.
New Zealand First would not support the bill as it stands, Mr Peters said, but would reconsider if an amendment was made in the committee stages to include the referendum.
"If they put an SOP [Supplementary Order Paper] in for referendum, then it will be all on.
"That's when we put all our cards on the table as to whether there should be Māori seats and, if so, should they be entrenched.
"There should be a two-part referendum," he said.