The Labour Party has selected Michael Wood as its new Mt Roskill candidate to take over from longstanding MP Phil Goff.
The selection was held early because of a possible byelection if Mr Goff wins the Auckland mayoralty in October.
Mr Goff is considered the front-runner and Labour leader Andrew Little appeared fairly certain of Mr Goff's success. He told the Herald that was a factor in the early selection.
"The reality is it's more likely than not that there will be a byelection at the end of the year because it is more likely than not that Phil Goff will be elected as mayor, so we needed to be ready."
Mr Goff has been the Mt Roskill MP since 1981, with a three-year break between 1990 and 1993.
He had a 8000-vote majority in 2014. Mt Roskill has traditionally been seen as a safe Labour seat although it has become more marginal, partly because of boundary changes.
In 2014, National got 14,275 party votes - 2000 more than Labour - but one quarter of National voters voted for Mr Goff.
A byelection could see the first real workout for the memorandum of understanding between Labour and the Green Party, if the Greens opt not to stand to boost Labour's chances. That is possible, given the Green Party only seeks party votes which are not a factor in a byelection.
Mr Little said the party vote results showed Labour was not a shoo-in.
"If you look at the polling, particularly the party vote, we've got our work cut out for us. But I'm confident that not only are the issues kind of going our way but we do have an outstanding candidate in Michael Wood and we will work darn hard to get him elected."
In 2014, Mr Goff benefited from split voting by about 3500 National voters, as well as a number of Green and New Zealand First voters.
Mr Wood, a Puketapapa Local Board member, has stood for Labour in the past in Epsom and the Botany byelection. He is also Mr Goff's electorate chairman and was given Mr Goff's endorsement early on.
The Mt Roskill electorate battle has already had its first mini-scandal after National List MP Parmjeet Parmar accused Mr Wood's partner Julie Fairey of trying to ban her from citizenship ceremonies. Ms Fairey, chairwoman of the Puketapapa board, claimed only electorate MPs could attend as part of the official party, not locally-based List MPs.
Mr Wood could attend as a Puketapapa Local Board member and Ms Parmar said Ms Fairey was trying to give him an advantage in any election campaign.
Ms Fairey retracted after she was told the ceremonies were public.