KEY POINTS:
National has doubled its lead over Labour in the latest Herald-DigiPoll survey, and it appears a series of attacks against John Key have had little initial effect on voters.
The poll shows National with 50.3 per cent support in the race for the party vote and in a position to govern alone if results were translated into votes at an election.
Labour is 13.5 percentage points behind on 36.8 per cent support.
The gap is now twice the 6.5 per cent lead National enjoyed in the Herald's July survey.
Labour dropped 5.2 points from July's poll. National and the Greens were the main beneficiaries of the lost votes.
The Greens crossed the 5 per cent threshold of party support in the Herald poll for the first time since May. NZ First remained below it.
Prime Minister Helen Clark's office last night attributed her party's flagging fortunes partly to the "backwash" from the departure of David Benson-Pope from the Cabinet.
A spokesman for the Prime Minister said the Herald-DigiPoll survey was registering that issue, and the publicity National had received from its annual conference.
The full effect of popular Government policies such as KiwiSaver, the extended Working For Families scheme, 20 hours' free early childhood education and cheaper doctors visits was still to be felt.
The Herald poll was conducted just after Labour mounted an orchestrated attack on Mr Key in Parliament, savaging his confused position on the transtasman regulatory agency for therapeutics, attacking his stance on whether New Zealand should have sent troops to Iraq and questioning his use of adjoining sections to build his Parnell home.
But his popularity seems unaffected because National has increased its lead and Mr Key has slightly narrowed Helen Clark's advantage in the preferred Prime Minister stakes.
She remains in front on 47.4 per cent support, but Mr Key has narrowed what was a 10.8-point gap in July to an 8.4-point one.
Mr Key said the poll was a continuation of a four or five month trend of support around 50 per cent for National.
"That's really good, but our focus is not so much on the polls, it's really on the issues that we think the country faces, including the economy, health and law and order."
