Act Party leader David Seymour says he is disappointed with the drop in his party's vote despite retaining the Epsom Electorate.

At a his party headquarters at the Royal New Zealand Yacht Squadron building on Westhaven Marina, Seymour said it was an election in which the minor parties took a "battering" but took encouragement that his would likely be one of only five parties in Parliament.

"We would like to have got a better result and more MPs in Parliament but we have to respect the will of the people on the night," he told the Herald.

Act's party vote of around 0.5 per cent was down to the election being dominated by National and Labour, he said.

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"It was very tough for smaller parties to get oxygen -- New Zealand First and the Greens lost seats, the Maori Party and United look like they're out of Parliament. We're still there - we held our ground."

During his speech to happy-enough but somewhat subdued supporters, Seymour said his party had done well in what was essentially a two-horse race.

"We'll be continuing to put on the agenda the critical moral issue that no-one else will touch in assisted dying; we'll be there to fight for education and choice in education; we'll be there to fight against government waste; we'll be there for all New Zealanders who are socially liberal and fiscally conservative, who believe in free markets and free minds," he said.

"I want to thank my neighbours in the Epsom electorate who have sent me again to Wellington to represent them, it's a great honour, and my door will be open at 27 Gillies Ave at 9am on Monday morning."

Richard Prebble, who Seymour referred to as "our former and greatest leader", said he was "delighted" that the party had retained Epsom but also reflected on a disappointing return on the party vote.

Seymour had run an "outstanding campaign" and was getting better and better as an MP.

"This is his first campaign as leader and I've been very impressed with him," Prebble said.

"[The party vote] is a great shame because if we got a few more MPs then perhaps National and Act could have had a Government alone."

Seymour went into this election with the backing of the National in Epsom and anything less than a victory in the country's wealthiest electorate would have been unthinkable for the party.

Act's headquarters, overlooking the shimmering Waitemata Harbour was filled with masses of yellow balloons, enlarged pictures of Seymour's boyish face and well-dressed bar staff serving tall glasses of wine and snacks.

Several hundred supporters attended, cheering the Epsom votes and tutting at as the party votes rolled in.

There was a noticeably young presence in the crowd with many under-30s and a surprisingly large number of under-20s there to support their 34-year-old leader.

Asked who the party's most ardent supporter was, Act's media liaison pointed the Herald in the direction of 18-year-old James Allan, who has been waiving yellow banners and delivering party mail for months now. He's been supporting Act since he was intermediate school.

"We've seen a much younger generation of Act supporters rising up," he said.

"In MMP we need strong right-wing support but also they're more liberal on issues such as euthanasia which really interested me."

Act's deputy leader Beth Houlbrooke said she had hoped to be "pleasantly surprised" tonight and be getting set to join Seymour in Wellington, along with the party's number three Brooke Van Velden.

"I think we ran an excellent campaign, we've had fantastic volunteers, a great line-up of candidates, we were really disciplined and we really didn't set a foot wrong.

"We just didn't get any cut-through and of course we're disappointed with the result."