KEY POINTS:
John Key's popularity has soared since he took over the National Party leadership 2 1/2 months ago, with 36.2 per cent of decided voters preferring him as Prime Minister in the latest Herald DigiPoll survey.
Prime Minister Helen Clark is still ahead of her main rival, on 47.7 per cent.
But Mr Key's rise has knocked her off her perch in the 50s where she has usually rated against former National leaders Don Brash and Bill English.
Mr Key's rating is not quite as high as Dr Brash's was at the peak of his popularity after his contentious race relations speech at Orewa in 2004.
A comparable rating of decided voters then put him at 41.9 per cent, but still below Helen Clark.
The impact of Mr Key's leadership can be seen in the narrowing of the gap between him and the Prime Minister.
When he had just taken over as leader she was ahead by 36.9 points, on 54.2 per cent. He was at 17.3 per cent, about where Dr Brash left off.
Helen Clark has fallen 6.5 points and the gap has narrowed to just 11.5 points.
It is a result that may please National more than its party vote lead over Labour because Helen Clark is regarded as a huge factor in Labour's success.
In party vote support, National has only slightly extended its lead over Labour to a 2.5 point advantage.
In the last poll, National had a 1.1 point lead over Labour - though a third of that poll was conducted during National's leadership change.
Labour can take comfort from the fact that there has been only a small change in the gap between the main parties.
In the past month, Mr Key received a lot of publicity, mainly positive, over his Burnside speech and Waitangi visit before the start of the parliamentary year last week.
Labour, on the other hand, has weathered continuing pressure over law and order issues and the performance of the Corrections Department.
It has also been embroiled in the departure of Mangere MP Taito Phillip Field from the party.
Support for all parties among decided voters shows little movement since the last poll - National is up 0.3 to 43.1 (which would translate to 55 seats), Labour is down 1.1 to 40.6 (51 seats) and the Greens are up 1.1 to 7.2 (nine seats).
Another comfort for Labour is that it would be much harder for National to form a Government, assuming that the party leaders who hold electorate seats keep them.
National would not be able to govern without the Greens' abstention or support but nor would Labour.
The poll also suggests that the previous gender gap between Labour and National supporters is narrowing. National has support from a greater proportion of women and Labour is getting more support from men.
* The party and preferred Prime Minister questions are of decided voters. For the party vote, 10.1 per cent of total respondents either refused to say, did not know or wanted no party.
The poll of 750 eligible voters was conducted between February 15 and 21 and has a margin of error of 3.6 per cent.
