Independent MP Hone Harawira says he will resign from Parliament next week, forcing a by-election in his Te Tai Tokerau electorate just seven months before a general election.
Mr Harawira made the announcement at the launch of his left-wing, pro-Maori party in Auckland on Saturday afternoon.
The launch of Hone Harawira's Mana Party attracted some familiar faces, including former Green Party MPs, trade unionists and academics.
Mr Harawira told the crowd he will resign from parliament on Tuesday setting in motion the process for a by-election in his Northland electorate.
He says every MP deserves the right to get a mandate from the people they represent, and that his party would be more accountable to its members.
Mr Harawira says the president of the Maori Party told him as recently as Friday that it would not stand a candidate against him this year, honouring an agreement made when Mr Harawira left the party in February.
Mr Harawira also set out some policies, including nationalising assets such as power, water and housing and ending state asset sales.
He says his party would seek to abolish GST and to replace it with a financial transaction tax, or what he labelled a Hone Heke tax, of 1 cent in the dollar.
The party would support nationalisation of any companies which have monopolies or are involved in a duopoly.
Death duty, capital gains and asset taxes have also been suggested.