Mr Harawira will resign from Parliament officially by writing to the Speaker on Monday, and thus set in motion the process for a by-election, the New Zealand Herald reported.
Mr Harawira, who quit the Maori Party in February, said his party would be an independent voice for Maori.
He told a gathering of about 300 people he was accountable to the people of his electorate and they should be able to have their say on his new party.
The Maori Party president assured him last night it would not stand a candidate against him this year, Mr Harawira said.
In a message to a unionist this week, Mr Harawira said Mana would be "anti-neoliberal, against monopoly capitalism, and against privatisation of the people's assets".
"The party and I will be pro-worker."
The strategy on taxes would be targeted at wealth such as capital gains taxes, death duties and asset taxes, he said.
"Let today be the day that we reject the politics of fear... Let today be the day we reject the politics of compromise because we deserve better than the weak accommodations we have now."
Mr Harawira also criticised spending such as "$36 million being wasted on this bloody yacht race in San Francisco".
