A jubilant newly elected Prime Minister John Key said his center-right National Party, with one seat shy of a parliamentary majority, will work for all New Zealanders.

"What an awesome night," he told thousands of cheering supporters at National Party headquarters in Auckland immediately after preliminary national election results were announced.

"I always said it would be tight but for the next three years there will be another National Party leading New Zealand. More people voted National today than three years ago and I want to thank each and every one of you," he said.

"Tonight New Zealanders voted for a brighter future and there will be a brighter future. I will continue to lead a government that serves the interests of all New Zealanders."

The results are preliminary and based on more than 2 million votes cast, Elections New Zealand said. Around 240,250 "special declaration" votes including 19,500 overseas votes, will be counted in the next several days.

Key's party took 60 seats, two more than in the 2008 general election but one less than needed for a majority in the 121-seat Parliament.

The weekend was a serious step backward for the main opposition Labor Party, led by Phil Goff, which lost nine seats for a total 27 in the coming Parliament.

The Green Party bolstered its seats to 13 from nine in 2008.

Despite being denied by an outright majority, National Party officials said they remain confident of the backing of the small Maori, ACT and United Future parties.

Key comfortably held onto his Helensville seat, with a 19,000-vote lead over Labor's candidate.

The New Zealand First Party took eight seats, the Maori Party took three while the three remaining seats were picked up by the ACT, Mana and United Future.

Key also took comfort in knowing that the National Party increased its popular vote from 45 percent in 2008 to nearly 48 percent this past weekend. Meanwhile, Labor slipped from 34 percent in 2008 to 27 percent.

"It's a pretty strong endorsement of where the government sits and we're confident we'll be able to build the relationships needed to go ahead with the program," party campaign manager Steven Joyce said on TVNZ.

Although unpopular with the public, the government has been selling off assets which could net up to $5.17 billion by 2015 when Key, a former banker with Merrill Lynch, wants the budget to be back in surplus by 2014-15. It stands at a record deficit of $13.6 billion.

Among assets slated to go is at least part of a 49 percent stake in the national airline Air New Zealand.

The National Party has earmarked the money from asset sales for investment in education and other services that are funded by taxpayers' money.

During the campaign, Goff heavily criticized the sell-off plan which most New Zealanders are against. He labeled the plan to spend nearly $740 million on schools over the next five years, with some of the money from asset sales, as "dumb." Once an asset is sold, it's gone forever, he said.

"You're flogging off the asset that provides ongoing support to social services in New Zealand without it having to come out of tax and once you've sold the assets you've lost the assets forever and you've lost the dividend stream," he said.