New Zealanders go to polls after a strange and dirty election campaign

An election campaign labelled New Zealand's strangest, dirtiest and most dramatic reaches a climax today as voters go to the polls, though it may take days or weeks before a government is agreed.

In the last month, conventional policy arguments have been squeezed to the margins, with the ruling National party forced to face down revelations of links to a notorious attack-blogger that hogged headlines for a fortnight.

That was followed by allegations of deception over state surveillance from US spying whistle-blower Edward Snowden and the journalist Glenn Greenwald.

In response, the National party leader and prime minister, John Key, consistently dismissed the allegations and attacked the messenger's motives.

Key has characterised both Nicky Hager, author of the book Dirty Politics, which draws on emails hacked from the venomous rightwing blogger Cameron Slater, and Greenwald, who arrived in New Zealand last week to expose contradictions in official positions on surveillance, as "conspiracy theorists".

In the short term at least it has worked. National party support has dropped a point or two in most polls, but so has that of the main opposition Labour party. A Colmar Brunton poll on Thursday put National on 45 per cent, Labour on 25 per cent and their likely coalition partner, the Green party, on 12 per cent.