ACT leader David Seymour has overtaken National's Judith Collins as preferred prime minister in the latest 1News Colmar Brunton Poll, with both major parties taking a hit.

Labour and National both dropped three percentage points, to 43 percent and 26 percent respectively.

On those numbers, Labour would be unable to govern alone.

ACT increased five percentage points to 14 percent, the Green Party was unchanged at 8 percent, and New Zealand First was up two percentage points to 3 percent, while Te Pati Maori was steady on 2 percent.

Jacinda Ardern remained atop the preferred prime minister rankings at 44 percent, but it was drama on the opposition benches with Collins' approval rating dropping 4 percentage points to 5 percent, below Seymour's 11 percent.

National MPs Christopher Luxon and Simon Bridges were nipping at Collins' heels with 3 percent and 2 percent.