National has shrugged off one of its worst weeks this year to record an increase over Labour in the latest Fairfax Nielsen opinion poll.
In a result that may surprise both major parties, whose internal polling had indicated loose lips caught on tape at National's annual conference in Wellington this month had hurt the Opposition, National has slightly increased its lead over Labour to 19 points.
Labour is steady on 35 per cent in the poll while National is up three points to 54%.
The Green Party suffered its worst result this term, falling below the 5% threshold to 4%. No minor party breached the threshold for seats in Parliament.
Voters seemed equally dismissive of the furore surrounding New Zealand First and its leader Winston Peters over secret donations to the party, with the party scoring 3%, down only one point on last month.
The Maori Party was steady on 2% and ACT steady on 1%. United Future failed to register.
National's increase in support flowed through to the preferred-prime minister rankings, with National leader John Key up four points to 43% support and Prime Minister Helen Clark down one point to 31%. Peters was down one point to 2%.
The poll was taken during one of the worst weeks for National this year, with the release of three recordings taken of National MPs at their annual conference.
The recording seen as most damaging was that of deputy leader Bill English, who said National would "eventually" sell Kiwibank. English was forced to apologise for his comments two days later.
At the time, Clark said the recordings were "a turning point" in the campaign and that their contents revealed a "secret agenda" by National.
Nielsen's findings appear to suggest that voters either did not care about the tapes or did not believe they were significant enough to change their vote.
The proportion of people who said they did not know who they would vote for was steady on 11%.
Translated into seats in Parliament, the disappearance of the Greens and New Zealand First would leave National with a commanding 70 seats 24 seats ahead of Labour on 46.
The Maori Party would be by far the largest minor party, assuming it wins six of the Maori electorates.
The slight widening on the gap between the two major parties this month arrests a three-month narrowing since May as Labour clawed its way back from a 26-point deficit.
Labour retains strong support from women, those on incomes under $40,000 and Maori voters but still lags considerably among male voters and those on higher incomes.
Backing for National has increased despite voter scepticism that the party will be able to deliver big tax cuts after agreeing to keep a swag of big-ticket Labour policies, including Working for Families and big spending on infrastructure.
Asked whether they thought National would still be able to afford "significantly bigger" tax cuts than Labour, 48% of voters said no and 35% said yes.
Nearly a third of National voters and almost 80% of Labour voters did not think National could afford bigger tax cuts.
Public pessimism over the state of the economy may be waning, with slightly more voters now believing their financial situation will improve in the next year. The number of voters who are more optimistic increased by three points to 45% over April, while pessimists declined from 39% to 30%.
Key said he thought voters had reacted negatively to a "dirty tricks" campaign over the secret recordings and may also have blamed Labour for them.
He said it was clear the public faced bigger issues.
"The economy is still front and centre stage. People saw it (the tapes) for the parliamentary theatre that it was. It doesn't affect their daily lives," Key said.
A spokesman for Clark said she was taking a "long-term view" of the election. "There is still a whole campaign to go."
Nielsen surveyed 1102 people between Wednesday, August 6, and Tuesday, August 12. The poll has a margin of error of plus or minus 3.1%.
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