The latest Taxpayers' Union Curia poll put National down 1.9 points on last month to 35.4 percent, while its coalition parties Act and New Zealand First remained mostly steady on 9.7 percent and 5.6 percent respectively.
Labour slipped 0.6 points to land at 29.4 percent, but the Greens bounced up 2.5 points to 12.7 percent. Te Pāti Māori was up 0.9 points to 4.0 percent.
On those numbers, the three coalition parties would have a majority with 63 seats between them, down three from last month, while the opposition would have 58, up two.
Prime Minister Christopher Luxon took a knock to his personal rating with his net favourability score dropping 13 points to -5 percent.
That was below Labour leader Chris Hipkins, who jumped 4 points to hit 3 percent.
The scientific poll surveyed 1000 people over three days last week and has a maximum margin-of-error of +/- 3.1 percent.
It captures the response to the coalition's first Budget where National delivered its promised tax cuts but broke its commitment to fund 13 cancer treatments from this year.
