Nobby Clark has taken the top job for Invercargill, ousting the country's longest serving mayor Sir Tim Shadbolt.

More than 50 percent of eligible voters took to the polls to herald in a new era for the city.

It was a packed field with 10 candidates vying for the mayoralty, but the results were clear less than two hours after polls closed.

The Invercargill City Council progress results showed Nobby Clark had more than 6500 votes followed by broadcaster Marcus Lush with close to 3800 votes and former deputy mayor Toni Biddle not far behind.

The results did not include special votes or votes cast after Friday, with just over 2000 votes left to be counted when the race was called.

It means a promotion for Nobby Clark from deputy mayor after a term in the council chambers.

"Really ecstatic about having the role, got quite a large margin so that's a real vote of confidence from the ratepayers in the city," Clark said.

Clark said his transparency and plans for action resonated with voters.

During his last term as councillor he had been keen to ensure plenty of progress on the many projects on the council's agenda, including the Southland Museum and Art Gallery, and he continued to oppose the Three Waters reform

"We've got quite a strong minded group there [in council], and that's what you want. I don't want a council that just sits around and rubber stamps staff reports. I want people to be up front and debating issues.

"But I also want us to do our homework before we do that in public, so people respect other people's voices. I think that's really important to have that."

He acknowledged outgoing mayor Sir Tim Shadbolt, and said the city would ensure they marked his legacy as a long-serving leader.

Sir Tim Shadbolt Photo: RNZ / Tess Brunton

Shadbolt said he was shattered not to have won a seat in the council chambers. He said he had not expected to be elected as mayor again, but after more than two decades in the top job he had hoped to continue as a councillor.

"Absolutely shattered. I couldn't believe it. I'd planned to have a celebration for getting on council, but I never saw it coming when it came to not getting any seat anywhere," Shadbolt said.

He wished the incoming council luck, and said they have a lot of work and projects ahead of them. He also offered his experience, and said he could act as an ambassador if the incoming council needed.

The term ahead would be challenging, with the hurdles including viruses and three waters reform, Shadbolt said.

"A lot of mayors around the country have lost their seat ... because of the complexity of the issues we're expected to deal with.

"But we've just got to pull together and hope we can face the challenges in a way that inspires the local people."

Invercargill City Council deputy electoral officer Michael Morris Photo: RNZ/ Tess Brunton

Council deputy electoral officer Michael Morris said the city's voter turnout was just over 50 percent - about what was expected.

"It looks like we're on average with where we normally finish up, so that is quite pleasing," he said.

He acknowledged it would be a new era for Invercargill with Sir Tim Shadbolt's long serving legacy.

"When I was coming home from Wellington... the taxi driver asked me how Tim was because Tim had once been in his taxi some years ago, [and] he always remembered him. I think that sums up Tim and his legacy."

The progress results showed sitting councillors Nigel Skelt, Darren Ludlow, Ian Pottinger and Allan Arnold would keep their seat.

Tom Campbell and Grant Dermody have been elected as new councillors, with other seats too close to be called.

"Our preliminary results should provide a clearer picture but it's likely it won't be confirmed until our final results are provided in the coming days, after special votes have been counted," Morris said.

Tess Brunton, Otago/Southland reporter

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Republished by arrangment.