How special votes could still affect the election result

The preliminary election results are in, but there's bad news for those hoping for a quick and painless outcome - tonight's count won't include a group of voters who could influence the final shape of the Government.

And it could take two weeks before we know their effect on the final result.

This year, people could enrol and cast their advance vote at the same time. While there's no data on who took up the offer of a democratic double-whammy, it appears to have been a particularly popular option for young and first-time voters, if Friday's half-hour-long line at the University of Auckland was anything to go by.

Those votes are classed as special votes - they take longer to process.

'Special votes' also include those cast from outside an electorate, people who enrolled after writ day (August 23), those on the unpublished roll and those who cast special votes because of a complication that meant accessing a polling booth would cause hardship.

In the 2014 election, 300,000 special votes were counted. Those votes saw the Greens gain a seat and National lose one. This time around, it's likely that number will be higher, because of those who enrolled and voted at the same time.

If the pattern of a left-wing preference among special voters holds true this election, it could well affect party-vote proportions for Labour and the Greens. That influence may be amplified by younger and first-time voters who cast special advance votes.

If the results are tight or if a smaller party squeaks just above or below the 5 percent threshold, those special votes may become a factor in the final composition of the next Government.  

The Electoral Commission says the target for final results is Saturday, October 7.