SMILING NOW: In one poll, John Key was up 3 at 42 per cent as preferred prime minister.

Two new political polls have confirmed a strong lead for National, although they disagree over the direction the trends are pointing.

A One News-Colmar Brunton poll puts National up a huge 6 percentage points since early April to 49 per cent - enough to govern alone - with Labour trailing on 33 (down 3).

The Green Party was down 4 points at 9 per cent.

NZ First was up one at 4 per cent, but still below the MMP threshold for list seats.

The Conservative Party was steady on 2 per cent and three small parties; the Maori Party, Mana and United Future; were all on 1 per cent.

John Key was up 3 at 42 per cent as preferred prime minister while David Shearer was down three at 12 per cent.

Meanwhile, a 3News Reid Research poll put National on 47.1, down 2.3, and Labour up 2.9 at 33.1 per cent. The Greens were up slightly at 12 per cent and NZ First slid 1.6 to 2.2 per cent.

The Maori Party was on 2.2 per cent, the Conservatives 1.5, Mana 0.5, ACT 0.2, and UnitedFuture 0.4 per cent.

It had Key on 40.7 (up 3.1 percentage points) as preferred prime minister with Shearer up 0.5 at 10.5 per cent.

The survey also asked respondents for their view of the Labour and Green party power policies, which aim to bring down energy prices by creating a single buyer of all generation.

It found 54 per cent supported the policies with 39 per cent against.

Among National voters 29 per cent supported the Labour-Green plan.