Hone Harawira's new political movement may be branding itself the saviour of the poor and downtrodden but before the Mana Party has even been officially registered it's set to cost taxpayers half a million dollars.

Harawira launched the party yesterday before a 300-strong crowd of supporters, including union heavyweights and Maori leaders Matt McCarten, Sue Bradford, John Minto, Nandor Tanczos, Annette Sykes, Margaret Mutu and Mereana Pitman.

It came barely an hour after the Act Party confirmed Don Brash as its leader in a secret board meeting at the Best Western Motor Lodge in Newmarket.

Brash intends to discuss former leader Rodney Hide's ministerial future with the Prime Minister this week, after ousting Hide.

At Te Mahurehure Marae in Pt Chevalier, Harawira's target audience was very different from Act's. He told them the Mana Party's basic aims were simple: to guarantee affordable food and shelter to all New Zealanders.

That meant rebuilding unions, introducing a "Hone Heke tax" of 1 per cent on every dollar spent and scrapping other taxes; and ending the 90-day probationary period for new employees.

"I want to recall the $36 million being wasted on a bloody yacht race in San Francisco and spend it instead on heating in the poorer suburbs of Christchurch," Harawira said.

But his other announcement - that he would force a byelection in his Te Tai Tokerau electorate - immediately sparked accusations of hypocrisy for incurring a $500,000 bill for taxpayers.

A spokesman for the Prime Minister said the announcement of a byelection would not push the Government to an early election.

He said Harawira was four weeks away from the six-month cut-off period in which byelections could not be held. "It's a complete waste of taxpayer money," the spokesman said.

Labour's Kelvin Davis, who stood against Harawira in Te Tai Tokerau in the last election, said the byelection would be a huge cost that wouldn't benefit anybody in the region. The party would decide this week whether or not he would stand against Harawira.

Labour leader Phil Goff said a byelection would be "farcical" as no sooner would the candidate be elected than he or she would be standing again at the November 26 general election.

But Harawira was defiant. "It's hardly an expense in terms of democracy," he told reporters.

He would write to the Speaker of the House on Tuesday informing him of this, effectively resigning from Parliament in order to stand as a candidate for the new party.

That would mean a byelection in roughly eight weeks - around June 25 or July 2 - according to chief electoral officer Robert Peden.

Maori Party co-leader Tariana Turia - currently in Russia for a conference - said she did not know if the party was standing a candidate in the byelection.

But she did much the same as Harawira before the 2005 election: quitting Labour and resigning her Te Tai Hauauru electorate to renew her mandate in a byelection.

Talking to the crowd yesterday, Mana's campaign director McCarten said he hoped to have 500 members signed up in time for the byelection so Harawira would have "Mana" rather than "Independent" beside his name on the ballot paper.