Act leader David Seymour looks set to retain the Epsom seat and provide National with a guaranteed coalition partner.
Seymour is more than 1100 ahead of National's Paul Goldsmith, with Labour's David Parker trailing almost 3000 votes behind.
With Act currently sitting on 0.5 per cent of the party vote, it is crucial Seymour wins the seat to keep the party in Parliament.
The 34-year-old entered Parliament in 2014 after winning the Epsom seat thanks in part to the endorsement of National leader and then Prime Minister John Key.
He replaced Jamie Whyte as leader of the Act Party after the 2014 election.
He first ran for Parliament as an Act member in 2005 where he stood against Helen Clarke in Mt Albert.
National has repeatedly asked supporters in Epsom to vote for Seymour as their electorate candidate while giving their party vote to National.
This allows Act to remain in Parliament as a guaranteed coalition partner.
Act will again be needed to make up a majority with National sitting on 46.4 per cent of the party vote with 32 per cent of the votes counted.