Almost 1 million people took advantage of early voting this week, the biggest ever turnout of advance voters in the country's history, according to CNN affiliate Radio NZ
Prime Minister Bill English's National Party -- which has run a minority government since 2008 -- led the main opposition Labour Party 45.1% to 41.9% in RNZ's final poll of polls Friday
That's a turnaround for National, which had been overtaken by Labour in some polls. But under New Zealand's proportional system, Labour may still be able to form a government with the support of the Green Party, which is polling at around 7.2%.
Political analyst Colin James advised caution on trying to make predictions or map trends onto the polls, pointing out that they have "bounced around during this campaign, with new bounces in the past two weeks."
At the start of the year, English -- who replaced former National leader John Key in December
-- was in a strong position and looked certain to continue Key's electoral success.
But a surprise decision by then Labour leader Andrew Little to stand aside at the start of the campaign made room for 37-year-old three-term member of parliament Jacinda Ardern.
After she took control of the party, it surged in the polls, leading the local press to coin the term "Jacindamania."
"Suddenly an alternative Labour-led government (was really) looking viable," Grant Duncan, an expert on New Zealand politics at Massey University, told CNN earlier this month.
Polls heading into Saturday's vote put the two main parties neck-and-neck, with a slight advantage for National in some surveys, according to CNN-affiliate Radio NZ
Voter engagement was high, with more than 800,000
taking advantage of early voting by Thursday, almost double the number who had done so at an equivalent point in the last election.
The election was largely focused on the economy, with National attempting to highlight its positive record, and housing prices, a key topic of attack for Labour.
New Zealand has the fastest rising house prices among major developed countries, according to data from The Economist, with a 13% increase in the past year. Labour had promised to built 100,000 new affordable homes if elected.
Polls are closed. The electoral commission said it plans to have official results published on October 7.