No-one has been elected as mayor of Wellington with a simple majority of votes on the first count since elections were first held under the preferential voting system in 2004.
Under the single transferable vote system, voters rank the candidates in their preferred order. If there is no candidate with a majority of votes, the lowest polling candidate is eliminated.
That candidate’s votes are redistributed according to voters’ second preferences. Each count is called an iteration.
The next lowest candidate is eliminated, and their preferences redistributed and so on until there is a winner. The preferences of voters whose most preferred candidate has been eliminated have, in effect, decided who will be the mayor.
In 2010 Celia Wade Brown beat the incumbent mayor, Kerry Prendergast, by just 176 votes on the final count, but only after the four other candidates were progressively eliminated.
The redistribution of the preferences of the third-placed candidate, Jack Yan, made the difference.
In mayoral elections from 1940 to 2001, mayors won a majority under the old first-past-the-post system in just seven out of 21 elections. In three of those elections, the winner was Frank Kitts, a very popular Labour mayor who served from 1956 till 1974.
The last mayor to win a majority was Mark Blumsky, who won 59 per cent of the vote in a field of six in 1998.
In 2004, the first election held under the preferential voting system, Prendergast was easily the most popular candidate on the first count with 22,069 votes, compared to 7703 for her nearest rival, Rob Goulden.
But it took five iterations for her to get a majority, and she won only when Goulden was eliminated and she picked up 30 per cent of his vote to beat councillor Bryan Pepperell. She increased her vote over the five iterations from 22,069 to 27,002 while the Pepperell went from 7993 to 18,115, because he gathered up more of the preferences of each of the eliminated candidates than did Prendergast.
In 2007, there were 11 candidates for mayor and Prendergast won only on the ninth iteration, despite starting with a massive lead on the first count – 17,990 votes over her nearest rival, Ray Apihene-Mercer on 6954.
Finally she got 21,866 votes to beat Pepperell on 10,125 votes. Her initial lead was decisive, because she secured more votes than her nearest rival in only three of the eight iterations. In the latter stages large numbers of voters had not expressed preferences for all candidates.
In 2010, Prendergast had a clear lead over Wade-Brown after the first count. But Wade-Brown picked up more preferences than Prendergast from the three liberal left candidates who were successively eliminated. She got 115 second preferences from Al Maunsell, then 327 from Bernard O’Shaughnessy, the second candidate to go.
Wade Brown then got 2420 of Pepperell’s preferences compared to 878 for Prendergast.
At that point Prendergast still led by 22,899 votes to 21,422 for Wade Brown, but her lead of 3249 votes on the first count had been cut to 1477 votes.
The last candidate to be eliminated was Yan. Voters who put Yan as No 1 choose Wade-Brown second by more than two to one over Prendergast – 3459 votes to 1806 votes – enough to put Wade-Brown into the mayoral chair.
This time around the two leading candidates are Wade-Brown, the current mayor, and longserving councillor John Morrison. According to opinion polls they lead the other four candidates, but neither has a majority.
Next come Yan and newcomer Nicola Young, and further back are lawyer Karunanidhi Muthu and former councillor Goulden.
If history is any guide, the two most important factors will be the number of votes that Yan and Young get, and who the voters supporting those candidates choose as their second and third preferences.
The way those preferences go will likely make the difference between Wade-Brown or Morrison becoming the mayor.