Key Points:

A strong gender bias in Helen Clark's support as preferred Prime Minister is evident in the breakdown of the latest Herald-Digipoll survey.

Among men, she draws 45.6 per cent support but 56 per cent of women say they support her.

The overall figure, of 50.8 per cent support, is 13.5 per cent points ahead of National leader John Key.

His support between the genders is more evenly spread: a slightly higher proportion of men support him, 39 per cent, compared to 35.9 per cent of women - the overall support for him is 37.3 per cent.

NZ First leader Winston Peters has 5 per cent support, a little down on his 6.6 per cent support last month.

But disproportionately more men support him, 7.2 per cent compared to 2.7 per cent of women.

The gender bias is there but less pronounced in party vote preferences.

National is still attracting disproportionately more support from men, and Labour is attracting disproportionately more from women.

The Greens get more support from women than men, as does the Maori Party but New Zealand First this time has attracted the same proportions of both genders.