Auckland mayor Phil Goff will not be seeking re-election this year.
"It's more than 40 years since I was first elected to office as MP for Roskill in 1981 and I believe it's time to pass the baton to a new generation of leadership," Goff said.
"It has been an absolute privilege to serve two terms as the mayor of Auckland, the city I grew up in and that I love.
"I want to thank the people of Auckland for having twice elected me by large majorities and for giving me the mandate to lead our city."
Goff's retirement has thrown the race for the mayoralty wide open at October's election.
So far Manukau ward councillor Efeso Collins, outspoken restaurateur Leo Molloy and Craig Lord, who came third for the mayoralty in 2019, have confirmed they are standing.
Goff, 68, paid special mention to his wife, Mary, and family for tolerating his absences at family occasions when council work had taken precedence, and to his mayoral office staff who had worked hard and competently.
"I would also like to acknowledge and thank deputy mayor Bill Cashmore for his huge contribution, and all those councillors from a variety of different political affiliations who have worked constructively with me to advance the interests of Auckland," said Goff.
He did not say what would follow come the end of his term.
"I will continue to give the role of mayor my full energy and commitment for the next seven months and will consider options for my future in due course."
In announcing his resignation he noted the impact Covid had had on civic operations, saying progress had been made in spite of the national health crisis.
"While the pandemic has created huge challenges, the city has made real progress over the last five-and-a-half years. We have made the biggest investments Auckland has ever seen in infrastructure for transport and water. This has reversed decades of underinvestment, where infrastructure spending did not keep up with population growth.
"We have taken big strides towards creating a sustainable environment, with measures to end the century-long problem of wastewater spilling on to our beaches and into our harbours, steps to contain the spread of kauri dieback, and predator control to revive our native bush and birdlife.
"As mayor, I am proud that I have been able to lead councillors to work collaboratively and constructively to meet the challenges of the pandemic and work towards our vision of creating a sustainable, inclusive and world-class city."
Goff said more than two million native trees had been planted as part of the Mayor's Million Trees campaign, and the current budget proposes strong steps to tackle climate change.
Auckland Council had also implemented a living wage for council employees and cleaning contractors.
As well as Collins, Molloy and Lord, Heart of the City chief executive Viv Beck is also expected to stand in an election tipped to be the first without a political heavyweight vying for the top job since the Super City was formed in 2010.
Beck is expected to announce her run for the mayoralty with the backing of the National Party's de facto local-body arm, Communities and Residents (C&R).
There has been speculation that another former Labour leader, David Shearer, could also stand for the mayoralty, but party sources say he has ruled it out.
Last week councillor Richard Hills announced he would not be running for the top role.
Hills, a North Shore councillor with Labour affiliations, had been working on a possible campaign since mid-2021.
However, he decided against pursuing the mayoralty, saying the timing was not right after just becoming a father for the first time.
Instead he would be standing for re-election this year in the North Shore ward, saying he had secured significant investment and wins for the community.