National leader Simon Bridges is up two points as preferred prime minister in the latest 1 NEWS Colmar Brunton poll.

Bridges, who has been in the job as leader for four months, pegged 12 per cent support, up two on last month's poll, 1 NEWS reported.

Prime Minister Jacinda Ardern was up four points to 41 per cent.

NZ First leader and Deputy Prime Minister Winston Peters was down one to 4 per cent, and National MP Judith Collins was sitting on 2 per cent, the same as last month.

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National remained the most popular party in the 1 NEWS Colmar Brunton poll, up one point to 45 per cent. Labour was steady on 43 per cent.

Both the Greens and NZ First dropped a point each - the Greens to 5 per cent and NZ First below the 5 per cent threshold.

The poll, of 1007 people was done after the Budget on May 17.