Labour list MP Phil Twyford says he will not be seeking the party's nomination for the Mt Albert by-election.
Mr Twyford lives in the electorate and had been seen as an early front-runner for the nomination.
But he says the by-election is an ideal opportunity to bring fresh talent into Parliament, building on Labour's 2008 intake of 13 new MPs.
If Mr Twyford had been selected by Labour and won the by-election, his list seat would have been filled by the former Auckland Central MP, Judith Tizard.
Radio New Zealand's political staff say there are concerns within Labour that Ms Tizard's return would not have helped with the rejuvination of the party.
The by-election, which will take place on 13 June, was triggered by the resignation of former Prime Minister, Helen Clark, to take up a top post at the United Nations.
Miss Clark had held the Mt Albert seat for Labour since 1981 and won it last November with a huge majority.
National's two main contenders are list MP Melissa Lee, and the party's unsuccessful candidate for Mt Albert at last year's general election, Ravi Musuku.