Former Prime Minister Jim Bolger says the MMP electoral system has reduced the power of voters and should be dumped.
Voters will be asked in a referendum on 26 November whether not New Zealand should continue to use MMP to elect Members of Parliament.
Mr Bolger was Prime Minister when New Zealanders voted by 54% to 46% in 1993 to ditch First Past the Post and replace it with the Mixed Member Proportional system.
He says it was a change brought on by a growing sense of that system's unfairness.
Mr Bolger believes MMP has weakened accountability and is now throwing his weight behind calls for change.
More about the referendum on the electoral system and the alternatives systems on offer can be heard on Insight on Sunday.