Nominations for the Labour Party leadership have closed, with David Parker, Grant Robertson, Andrew Little and a last-minute bid by Nanaia Mahuta yesterday.
The contest was triggered by the resignation of leader David Cunliffe a week after the general election on 20 September, in which Labour's share of the vote fell to an historic low of just over 25 percent.
The leader will be chosen by an electoral college made up of 40 percent caucus votes, 40 percent from party membership and 20 percent from affiliated unions. The first hustings meeting is in Wellington on 22 October and the winner will be announced on 18 November.
Meet the candidates:
Before becoming a lawyer for the Engineering, Printing and Manufacturing Union, Andrew Little studied at Victoria University in Wellington where he was active in the campaign against the student loan scheme.
He rose up through the ranks in the union, becoming national secretary in 2000 - a position he held until 2011. Mr Little was also president of the Labour Party from 2009 to 2011.
Mr Little stood for Parliament in 2011 in the New Plymouth electorate. Failing to win the seat from National Party incumbent, Jonathan Young, he entered Parliament as a list MP.
He again ran for the seat unsuccessfully in the 2014 election, keeping his place as a list MP. However, he was risk of losing the seat as the last person in on Labour's list under the provisional results - his seat was confirmed under the final results.
Mr Little has been endorsed by former leader David Cunliffe, who withdrew from the leadership the day before nominations closed.
Nanaia Mahuta (Waikato-Maniapoto, Nga Puhi) entered Parliament as a list MP in 1996, then won the Te Tai Hauauru seat the following election.
She grew up at Waahi Pa in Huntly and attended the local Rakaumangamanga School and Diosecan School in Hamilton. She graduated with her BA and then MA (Hons) in Social Anthropology at Auckland University.
Ms Mahuta has close ties to the Kingitanga movement as she is the eldest daughter of the late Sir Robert Te Kotahi Mahuta, who was the adopted son of King Koroki and the elder brother of Te Arikinui Dame Te Atairangikaahu.
She was a minister in the previous Labour Government, holding portfolios including Customs, Local Government and Youth Affairs. Currently, she is spokesperson for Maori Affairs and Treaty Settlements, and the senior Maori vice-president of the Labour Party.
Ms Mahuta held her Hauraki-Waikato seat at the 2014 election with a majority of 7695 votes, an increase of 1760 from her 2011 result in the seat.
David Parker studied law and business at the University of Otago, and co-founded the Dunedin Community Law Centre.
He was first elected to Parliament in 2002, winning the Otago seat from National's Gavin Herlihy. However, he was defeated in that seat in 2005 by National's Jacqui Dean and has been a Labour list MP ever since.
He was a minister in Helen Clark's government, holding portfolios including Energy, Climate Change and as Attorney-General.
In March 2006, Mr Parker stepped down as a minister while an investigation was held into allegations he had filed an incorrect declaration form to the Companies Office. He was cleared and reappointed to the Cabinet by Helen Clark a few months later.
Mr Parker initially put himself forward as a candidate in the 2011 leadership contest, but early on withdrew his bid and threw his support behind David Shearer. He became deputy leader after Mr Cunliffe was elected leader in 2013.
Mr Parker was appointed acting leader after Labour's disastrous election defeat in September 2014, with Annette King his acting deputy. He will remain as acting leader during the leadership contest, with Ms King fronting most issues in the media.
Grant Robertson began his career with the Ministry of Foreign Affairs and Trade in 1997, after studying politics at the University of Otago. His first foray into national politics was as a ministerial adviser for Marian Hobbs; he then moved into Helen Clark's Prime Ministerial Office as second in charge to Chief of Staff Heather Simpson.
He took a term out away from Parliament after the 2005 election, working for the University of Otago, based at the Wellington School of Medicine.
Mr Robertson inherited the Wellington Central seat from Marian Hobbs in 2008 and has held it through the past two elections.
Following the 2011 election loss under Phil Goff and Annette King, he was appointed deputy under new leader David Shearer.
In 2013, after Mr Shearer resigned, Mr Robertson contested the leadership against Mr Cunliffe and Shane Jones under the new party rules giving party members and affiliated unions, as well as MPs, a vote on the leadership.
Although he won the most caucus support, Mr Robertson was beaten by Mr Cunliffe through the party member and union votes. He was subsequently replaced by Mr Parker as deputy.