Labour MP Shane Jones will try to topple Maori Party co-leader Pita Sharples in next year's election by challenging for his Tamaki Makaurau seat.
Mr Jones has confirmed to the Herald he will seek the nomination to stand for Labour in the Maori electorate, which has been Dr Sharples' stronghold since the Maori Party entered Parliament in 2005.
His challenge will end an apparent tacit agreement by Labour not to stand strong candidates against the two Maori Party co-leaders, who rely on their electorate seats rather than the party vote to be in Parliament.
It will at the least cause Dr Sharples some discomfort in the seat where half the voters gave their party vote to Labour last election.
Mr Jones has taken a no-holds-barred approach to the Maori Party, and especially its leaders, since it became a support partner for National.
Although the Maori Party has consistently expressed willingness to work with either of the major parties in government, Mr Jones said it had become "listless and torpid" with National. He believed it was time for a "more aspirational voice in Maori politics".
"I think anyone who spends even a smidgen of time looking at politics knows the Maori Party is wedded to the National Party.
"So this will give them a clear choice. If they want to continue to maintain the powerbase of the National Party, then vote for Dr Sharples.
" If you want to return to a Labour government, vote for Labour's candidate."
Although Dr Sharples won the seat with a 7540 majority in 2008, he was up against a comparatively weak Labour candidate in Louisa Wall, who openly said she intended to go for the party vote rather than the electorate vote.
Labour won 50 per cent of the party vote in 2008 - 10,084 votes compared with 5801 for the Maori Party - giving further grist to Mr Jones' argument that the Maori Party sold out its voters by going with National.