Winston Peters would hold the key to the Beehive's ninth floor if an election was held now.

The latest Roy Morgan opinion poll shows even though New Zealand First's rating dropped to 9.5 per cent, it would still be in a position to decide who the next Government would be.

Both National and Labour's rating increased by around three percent in the latest poll, but the Greens dropped two and a half per cent to put it on 12.

Labour and The Greens rate 41.5 per cent combined compared to National on 45.5 per cent, leaving Winston Peters as the kingmaker.

59 per cent of voters say the Government is heading in the right direction compared to just 29 per cent saying they've got it wrong.