Click here to view Herald graphics detailing the poll resultsKEY POINTS:
National leader John Key has overtaken Prime Minister Helen Clark in popularity in the latest Herald-DigiPoll survey, and his party has extended its lead over Labour to 18 points.
It is the first time since May last year that Mr Key has been ahead of Helen Clark as preferred prime minister, although his lead is only two points.
National has been ahead of Labour since Mr Key became National leader in December 2006 but apart from a surge in his popularity in May because of his role in the anti-smacking-bill compromise, Helen Clark has convincingly led the preferred prime minister polling. That has reinforced the view that despite poor party polling, she is Labour's strongest asset.
But in the past month, Mr Key and the National Party have both gone up 7 points in the survey.
Mr Key is preferred by 46.3 per cent of decided voters and Helen Clark by 44.3 per cent in the poll, conducted between February 11 and 28.
In January, Helen Clark was ahead of Mr Key by 10.5 points.
New Zealand First leader Winston Peters polled 3.3 per cent. Trade Minister Phil Goff, often tipped as the next Labour leader, scored no support as preferred prime minister.
The gap between the two main parties is so wide and coalition partners so limited for Labour - the Greens are below 5 per cent - that National could easily govern alone if the poll's figures translated to votes.
National is on 54.5 per cent (up 7 points), 18 points ahead of Labour on 36.5 per cent (down 2.2).
In the January survey, the gap between the parties was only 8.8 points.
However Helen Clark this morning told Newstalk ZB surveys were volatile and voters had not yet focused on the election.
"The movement for our own party is within the margin of error," she said.
"There's a tremendous amount of volatility in these polls...we know we've got a lot of work to do but I'm determined to be out there with the best plan for the future of New Zealand."
Miss Clark said she thought that when people focused on the election campaign this year they would see Labour was rolling out big policies.
"I haven't got the slightest intention of cruising to defeat," Miss Clark said.
"I'm in there to make this a highly competitive race."
A Marae-DigiPoll released yesterday indicated the Maori Party would win all seven Maori seats if an election was held now.
Miss Clark said on TV One's Breakfast programme she wasn't taking the poll seriously because of the small number of voters questioned in each of the Maori electorates.
"There would be about 95 people on average in each of those seats polled...I'm told the margin of error would be somewhere between 11 per cent and 19 per cent," she said.
"At that point, you've got a lottery."
Gender bias between the two leaders persists - men disproportionately favour Mr Key and women disproportionately support Helen Clark as prime minister.
The poll shows that voters aged over 60 have a strong bias towards National and New Zealand First.
It also shows that New Zealand First supporters have a strong preference for a coalition with National over Labour (90 per cent v 9.1 per cent) and that Maori Party supporters are not overwhelmingly disposed to a Labour deal - 57.1 per cent of Maori Party supporters would favour a deal with Labour, but 42.9 per cent would favour a deal with National.
The poll was conducted after an intense political start to the year in which both leaders made "state of the
nation" speeches and announced policies on youth crime, education and training.
Polling began after both leaders visited Waitangi, where Mr Key's meeting with Tame Iti received top billing, as did Helen Clark's aversion to Te Tii Marae.
Helen Clark hinted at media bias, saying last night through a spokesman: "Obviously the Leader of the Opposition has had a lot of publicity since the beginning of the year." She believed Labour polling was holding up and was reasonably close to the 1999 result - 38.74 per cent - when Labour took office.
"The important issue now is who has the best plan for the future," she said.
Mr Key did not believe he'd had more publicity than Helen Clark at the start of the year "and in fact she got enormous coverage from the [Sir Edmund] Hillary funeral ... not that that was political."
He believed they both received extensive, though contrasting, coverage at Waitangi.
He said he never thought his hongi with Tame Iti would damage him in the eyes of the voting public.
"I thought the mood of the nation has moved on and they started looking at Helen Clark fighting the battle that has been and gone and I think they responded positively to me wanting to engage and make a day of national celebration rather than harbouring some sort of historic dispute."
Support for the Greens is showing some volatility, falling to 4.4 per cent from 9.1 in the previous poll and 3.5 in the one before that.
New Zealand First is down 0.7 points on 2.1 per cent.
Falling below the 5 per cent threshold means neither party would win seats in Parliament unless they won an electorate.
Mr Peters has not yet confirmed that he will try to regain his former Tauranga seat, won last election by National's Bob Clarkson.
The Maori Party polled 1.5 per cent (up 0.5), United Future 0.4 (up 0.4), Act 0.4 (down 0.3) and the Progressives were unchanged on zero.
Tax cuts remain the issue most likely to influence votes, 20.7 per cent of those polled listing it top.
* The poll was of 734 respondents, and results presented are from decided voters only. The percentage of undecided voters was 17.7 per cent. The margin of error is 3.6 per cent.
