Wellington's two main mayoral contenders think the switch from first- past-the-post to the single-transferable-vote system may have played a part in the close election result.
Provisional results put incumbent Kerry Prendergast ahead of Celia Wade-Brown by just 40 votes.
The final result will be known on Wednesday after the counting of 963 special votes.
Both candidates think the switch to single transferable voting played a part in Ms Prendergast losing her 11,000 vote majority of the last election.
Ms Prendergast also says she knew it would be a tough race when she sought a fourth term in office.
She says her work as vice-president of Local Government New Zealand has taken time from working on Wellington issues, but says she tried to strike a balance.
Ms Wade-Brown says that in the past special votes have gone against the incumbent, though every election is different.
Wellington public transport advocate Brent Efford says Ms Wade-Brown's support for sustainable transport attracted many votes.
But Jo Bransgrove of the Wellington Employers' Chamber of Commerce disagrees, saying a survey has shown 87% were in favour of the Transmission Gully road project, and its research shows most Wellingtonians are keen to have a good infrastructure.
Former Wellington city councillor David Shand, who sat on the Royal Commission on Auckland Governance and chaired the rates inquiry in 2007, says it's the first time Ms Prendergast has faced stiff opposition.
By Sunday, most of the votes had been counted twice and reconciled. Electoral officer Ross Bly said that, once verified, the special votes will also be counted twice and reconciled.
Mr Bly says voter turnout was slightly more than 40%. Turnout in previous years was: 36.76% in 2007; 42% in 2004; and 46% in 2001.
Confusion persists - officials
Officials are reporting a small improvement on the number of vaild votes cast in this year's local body elections, but say there is still confusion over the two voting systems used.
The final numbers are not in, but Electionz.com, which processes votes for a number of councils and health boards, says there appear to be slightly fewer invalid votes than normal.
Wellington City Council's electoral officer, Ross Bly, also says the number of invalid votes appears to be down on the last election.
He says problems arise when voters have to switch between ranking candidates under STV, and putting a tick beside their name under FPP.