NZ First says it will hold a binding referendum on whether to retain or abolish Maori seats if it governs after the September election.
A second referendum question will ask whether or not the size of parliament should be reduced to 100 members. The current parliament has 119 MPs.
Both will be held mid-term on the same day.
NZ First leader Winston Peters announced the policy yesterday in a speech at the party's pre-election annual meeting.
He said four Maori seats were introduced in 1867 and in 1986 a royal commission on the electoral system recommended the Maori seats be abolished should MMP be adopted.
"Since 1867 all the way into the early 1980s only four Maori ever got to parliament not in a Maori seat," Mr Peters said.
"Today I see a number of Maori in parliament who are the match for anyone else there. And their combination of political skills will place them in the elite in parliament."
MMP was adopted effectively from 1996 and the increase in Maori representation was dramatic. In 2014, 22 per cent of MPs identified as Maori, Mr Peters said.
The 72-year-old Mr Peters is of Maori descent on his father's side while his mother is of Scottish descent.
He's seen as a potential kingmaker after the election, and his party has about 11 per cent support in polls.
"This country is headed for a political upset," Mr Peters said.
"What's happening in NZ is that people have simply had a gutful, where the poor have been bypassed and the middle-class have been left behind."
He says NZ First will "put the brakes on the wholesale flogging off of our land and other sources of wealth to foreigners".
NZ First will also make state-owned KiwiBank the government's official trading bank.
"It is absurd that a foreign bank Westpac should be clipping the ticket on all the NZ government's business and financial transactions," he said.
Westpac is based in Australia.