TVNZ seems to be the only media outlet commissioning and running stories on political polls on an even vaguely regular basis (the Roy Morgan ones are out there but much lower profile). Which means they dominate political discourse more than single poll results probably should.
Having said that, the poor result for Labour seems plausible (they were also on 28 in the latest Roy Morgan). The party has moved to the far left for the first few months of 2016 and it hasn’t gone well. I think there are a few things driving this: Bernie Sanders and Jeremy Corbyn have excited the imagination of many left-wing political activists and there’s a desire to try and replicate that dynamic here. But those guys are operating in polities totally different to anything like the conditions in New Zealand. I also think that many in Labour are invested in a cyclical theory of politics in which what they’re going through now is equivalent to what happened to National during the 2000s. Which is a comfortable thing to think, because if true it ends with them being swept to power again sooner or later. And part of National’s rebirth involved a move to the far right under Don Brash. Shore up the base and then attack from a position of strength! So they keep trying the inverse of that.
But if you look at more recent history, their poll results under the centrist leadership of Shearer went as high as 36%. Then he was rolled, Cunliffe took the party to the left, and they wound up in the mid 20s. Then Little came in and seemed more moderate, and the poll results went up. But this year they’ve campaigned on free tertiary education, a UBI, fuck the TPPA etc, with a subsequent decline in support and they’re back in the 20s. It kind of seems like the voters are telling them something here.
I complained bitterly about Shearer’s centrism at the time, and I’m sympathetic to the forces moving the party to the left. But there don’t seem to be many voters available to them there, and plenty of voters available in ‘the centre’.