Winston Peters' surge tricky for most polls to pick

Winston Peters greets supporters. The polls underestimated New Zealand First's last-minute surge. Photo / Getty

The Herald-DigiPoll survey was among the most accurate of those taken in the last few days before the election and - barring the last Roy Morgan poll - was the only one to indicate the strength of Winston Peters' last-minute surge.

Of the six main political polls, the Horizon poll was way off the mark in under-reporting support for National.

The Roy Morgan poll conducted between November 22 and 24 proved the most accurate in predicting National's support, putting it at 49.5 per cent, just 1.5 points beyond the 48 per cent actual outcome.

However, it put Labour at 23.5 per cent, against the election-night tally of 27 per cent, and had the Greens at 14.5 per cent, almost four points higher than Saturday's result.

The Herald-DigiPoll survey, on the other hand, had National almost three points higher than its election-night tally and Labour two points higher. It did well in putting the Greens' support at 11.8 per cent, just a point above the actual outcome.

But while the 3News-Reid Research, One News-Colmar Brunton and Fairfax Research polls had Mr Peters' NZ First below the crucial 5 per cent mark, Roy Morgan was just a few pips short of a bullseye, putting the party at 6.5 per cent against its actual result of 6.8 per cent. The Herald-DigiPoll survey had NZ First at 5.2 per cent.

National Party member and pollster David Farar said all six of the main polling companies barring Horizon did "broadly okay" in predicting National would be re-elected but wouldn't need the support of the Maori Party.

The closer to election day the polls were conducted, the more accurate they tended to be.