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.