The Green Party has hit a record high 17 per cent support and National have taken a big hit in a new political poll released today.

The Roy Morgan survey shows National down 4.5 per cent to 44 per cent since the previous polling period that ended on March 11 - virtually a straight switch of support with the Greens who were up 4.5.

But there is little good news for Labour, which was up a marginal 0.5 percentage points at 30.5 per cent.

The poll contrasts with last week's One News survey that had National solid on 51 per cent.

The latest Roy Morgan poll was taken between March 12 and April 1, covering the controversy over ACC and minister Nick Smith's resignation. It polled 948 respondents.

It had the Maori Party on 1.5 per cent (up 0.5), ACT unchanged on 0.5 per cent and United Future also level on 0.5 per cent.

The result, if it was reflected in a general election, would put a Labour-Green coalition in the box seat to form a Government, though it would likely need the backing of NZ First which was unchanged on 5 per cent.

Mana Party support was steady at 0.5 per cent.