The once-red "people's republic of Christchurch" has become the bluest of all the country's five main cities after a spectacular leap in support for the National Party following the city's devastating earthquakes.
National support in the seven Christchurch seats, including Waimakariri and Selwyn on the city's outskirts, jumped from 44.2 per cent at the last election to 51.9 per cent - higher than in Auckland, Hamilton, Wellington or Dunedin.
In contrast, the party's support crept up only 1 percentage point in Auckland, 2 points in Hamilton and 3.4 points in Wellington.
If NZ First is counted as part of the "centre-left" along with Labour, the Greens, Mana and the now largely defunct Alliance Party, there was actually a 2.3 per cent swing to the centre-left in Auckland and only a 0.6 per cent swing to the centre-right nationally.
The rightward national swing was driven by a massive 5.9 per cent swing in Christchurch.
Labour's Christchurch East MP, Lianne Dalziel, said the swing was in line with international experience showing that voters usually swing in behind incumbents after any disaster.
"I have done a lot of research on recovery post-disasters. This is very familiar," she said.
"There is a period of time within which the leaders at the time of the disaster enjoy popular support. Then, if things don't turn out well, they get blamed."
She said Christchurch Mayor Bob Parker enjoyed the same phenomenon last year. He had been trailing veteran left-wing MP Jim Anderton in polls before the first earthquake in September last year, but won easily after the quake.
"The next election will be completely different," Ms Dalziel said.
The results were also affected by around 8900 people who have left Christchurch since the earthquakes. The election-night turnout of only 23,813 voters in Christchurch Central was lower than in any other general electorate except Mangere, Manurewa and Manukau East, and about 9000 lower than in nearby Selwyn and Waimakariri.
However, many people who have moved out may still be registered in Christchurch Central and Christchurch East. They may have cast special votes, either from elsewhere in New Zealand or from overseas, and those votes have yet to be counted.
National MP Kate Wilkinson, who won the Waimakariri seat from Labour's Clayton Cosgrove in one of the biggest upsets on Saturday, said her roll was up by 3000, reflecting both the exodus of quake refugees and long-term population growth in the district.
The result is a dramatic reversal of Christchurch's reputation as a Labour stronghold. Former Business Roundtable head Doug Myers famously labelled it the "people's republic of Christchurch" in 1998 when its Labour-led council refused to sell its airport.
Even though Labour has hung on to the electorate vote in Christchurch East, Port Hills and Wigram, and is in a dead heat with National in Christchurch Central, National's party vote is now higher than Labour's in all of the city's seven seats.
Nationally, National's party vote is higher than Labour's in 12 of the 19 general electorates that Labour won.
Again, Christchurch East is the most extreme case. Ms Dalziel won 55 per cent of the electorate vote - apparently gaining from the same incumbency effect that helped National in the party vote - but National won 46 per cent of the party vote to Labour's 32 per cent.By Simon Collins Email Simon