The most recent Curia Public Poll Average has Labour on 29.5% and the Greens on 13%. This would put a Labour/Greens coalition neck and neck with National. If these numbers are representative of how the electorate votes in September, then a centre-left government is plausible. And yet, National would remain the single largest party by a wide margin. Nevermind policy. That is the reason why red/green is a radical proposition.
Since World War II, power has alternated between Labour and National at regular intervals. Some have compared this pattern to the swing of a pendulum. When the Clark Government was defeated in 2008, a lot of people assumed that the pendulum would swing back to Labour after two or three terms. There is no evidence that has happened. The Labour vote declined in 2011 and 2014. The party now struggles to poll 30%, and if historical trends are anything to go by then we can expect its support to decline further as the campaign gets underway.
Yet the possibility of a centre-left minority government cannot be dismissed. Such an outcome would, most likely, depend on the support of Winston Peters and NZ First. In the past, NZ First has given preference to the party with the most seats. Will 2017 be an exception? If so, then the electoral pendulum would have swung, not to Labour, but to Labour/Greens/NZ First. It would be our first, true multiparty government.