The Labour Party candidate for the Mount Albert by-election is defending comments he made over the use of private security forces in war-torn countries.
David Shearer, 51, who is leaving his job heading up the United Nations' humanitarian operations in Iraq, emerged the winner of eight candidates for Labour's nomination on Sunday.
The Green Party's candidate, co-leader Russel Norman, has criticised Mr Shearer's comments on the use of mercenaries.
Mr Shearer says he made the comments in Sierra Leone in 1999 during the civil war, when the government hired was unable to get any international help to combat rebel forces were mutilating women and children.
He says the government employed a company to help train its military forces, and it was the use of such contractors that eventually helped lead to elections being held in that country.
National last week also highlighted differences of opinion between Mr Shearer and Mr Goff over the use of private security contractors in war-torn countries. Phil Goff says Mr Shearer's selection shows the National Party's dirty tricks campaign failed.
Russel Norman has also said is the only "progressive" candidate since Mr Shearer comes from the right-wing of Labour.
David Shearer says he is totally committed to Labour and Mt Albert, and will spend the next six weeks knocking on doors and talking on street corners.
He says the by-election will be fought on local issues - such as public transport and the Government's super-city plan for Auckland.
Mr Shearer has unsuccessfully stood for Labour twice previously, on the party list in 1999 and in the Whangarei electorate in 2002. He worked for two years in Labour leader Phil Goff's office when he was foreign minister.
The ACT party candidate, list MP John Boscawen, says his team aims to knock on 15,000 doors before polling day, and despite the odds being stacked against his party, anything could happen.
The by-election for the seat, which was held by former Prime Minister Helen Clark, will take place on 13 June.