Defeated Christchurch mayoral candidate and Wigram MP Jim Anderton will retire from Parliament next year.
Anderton lost to Bob Parker, who retained the mayoralty by a margin of more than 16,000 votes after the Canterbury earthquake.
Anderton, 72, said he had "piles of work to do" despite his mayoral loss, including electorate issues, policy work, and helping earthquake victims.
"It's people that are the centre of my motivation," he said. "If people need help, they get it."
Anderton said he did not feel bitter about his loss, despite holding a substantial lead in pre-earthquake polls.
"I have one philosophical position on these matters, which has served me well: you worry about things you can do something about, and I can't change an earthquake."
He was "sure" he would have won the mayoralty if the earthquake had not hit Christchurch.
Anderton reiterated his belief that Parker's withdrawal from the election campaign had dented his comeback chances.
"It's the first time I've ever been in an election where there was no election campaign, and you couldn't get to grips with the issues you really stood for.
"It focuses everyone's mind, as it was meant to do, on the last four or five weeks."
He said Parker had done a good job of leading the council's post-earthquake response but warned he could not ignore earlier concerns about a lack of accountability and transparency.
Anderton confirmed he would stand down from Parliament at the 2011 election, but would continue his work in the community.
He was working on a book about Kiwibank, and was planning to spend more time with his family.
"I've got a few grandkids that I don't see as much as I should ... my wife was as close to celebrating as you can get when your husband loses a mayoralty race, because she gets her life back."
He acknowledged his retirement would mean the end of his Progressive Party "in an informal sense".
However, he said he had worked with the Labour Party to ensure current and former party members, including potential Wigram successor Megan Woods, would be able to move on politically.
"I've made sure there's a pathway in my absence ... we've made sure that our best and brightest have an avenue to serve in Parliament."
- The Press
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