Invercargill city councillor Toni Biddle will stand against Mayor Tim Shadbolt at the local body elections next year.

The race for the Invercargill mayoralty is on, with city councillor Toni Biddle announcing she will take on incumbent Tim Shadbolt at next year's local body elections.

Biddle is the first to publicly reveal plans to stand against Shadbolt - the longest serving incumbent mayor in New Zealand.

Biddle, 42, said she respected Shadbolt, but believed Invercargill needed a mayor who was dedicated to the city as it went through big changes.

Kavinda Herath Invercargill Mayor Tim Shadbolt has welcomed news councillor Toni Biddle will stand against him at the 2019 local body elections.

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Shadbolt had created a "brand" which had made him a celebrity, which in turn took him out of town.

The mayor of Invercargill needed to be available to listen to the people and be on the ground amongst the community, she said.

"At this time of transformation we need that leadership more than ever and I believe I can deliver that."

Shadbolt welcomed the news Biddle would stand against him next October, saying it would liven up the election.

He accepted he was not always in Invercargill but he was making no excuses for that.

"I am a different sort of mayor, I am not office bound."

The disadvantage was he didn't attend as many meetings, but the advantage was he put the city on the map.

"I can't do that bound to a desk."

He expected at least three or four people to stand for the mayoralty.

Biddle, born and bred in Invercargill and in her first term as a city councillor, said the last election had brought about a lot of change but "somewhere along the line" the people had been forgotten.

She quoted a Maori proverb, whakatauki.

"What is the most important thing in the world? it is people, it is people, it is people."

She rattled off changes taking place or due to happen, including the CBD redevelopment which was "exciting" but impacted on the livelihoods of retailers, the museum closure which affected the community, people wanting to build were battling consent processes, the housing shortage, the "unnecessary" proposal to close the Bluff Transfer Station and the new council chief executive's change in culture which had affected staff.

Change was positive and necessary for Invercargill to be a relevant city, but it was about how it was delivered, and the mayor's role was integral to that, she said.

"At this time of transformation we need that leadership more than ever and I believe I can deliver that."

She had told Shadbolt of her decision to stand.

He had been "surprisingly supportive" and had offered to mentor her.

Shadbolt said he was prepared to give advice to anybody who asked him.

A former champion Southland swimmer and a singer, Biddle's work history includes 11 years at the Ministry of Social Development, a jillaroo mustering sheep on stations in the Australian outback and travel broker.

She is now a fulltime city councillor and recently married to Kris Maclellan they have three boys aged 6, 13 and 23, with a grandchild on the way.

She accepted some people would say she was too inexperienced to take on the mayoralty, given she was in her first term as a councillor.

However, she said her experience on the Southland Museum and Art Gallery trust board, in which she was made chairwoman five months before it was closed due to safety concerns, held her in good stead.

Decisions made before her time impacted the council's decision to withdraw the staff from the museum, she said.

She had fronted the decision to close the museum with integrity and it was her hardest challenge.

"I am a leader and more than capable of being the mayor, and want the community to consider that."

She had no qualms about running against Shadbolt the brand.

"If you are going to run, you may as well run against the legend.

"There's no point waiting for him to retire because I don't think he has any intention of doing so."

She would also stand for a councillor's seat on the council.