Labour's support has jumped under new leader David Cunliffe to the extent that he could form a coalition government and become Prime Minister, if today's Herald-DigiPoll survey figures were translated to an election result.
It is the first political poll conducted entirely since he became leader.
The poll also shows a marked dive in the popularity of John Key, to the lowest level since he became Prime Minister.
Labour has gained 6.8 points to 37.7 per cent of decided voters which would give it 48 seats.
With the Greens' 14 seats and the Mana Party's one seat, it would be able to form a government of 63 seats in a Parliament of 124 seats.
Polling began two days after Mr Cunliffe won the leadership contest against Grant Robertson and Shane Jones.
From the moment David Shearer resigned on August 22 to the declaration of the new leader on September 15, the contest was conducted in a blaze of publicity.
The rise of Labour appears to be mainly at the expense of National, which is down 5.1 points since the June poll to 43.7 per cent support.
National would not have enough support to form a government with present support partners Act holding the same number of seats as they do now.
And even if its other support partner, the Maori Party, kept its present three electorate seats, National's 56 seats plus five for its support partners would still not be enough to form a government.
PREFERRED PRIME MINISTER
Mr Key's support as preferred Prime Minister has fallen 9.4 points to 55.8 per cent.
Since becoming Prime Minister he has been in the 60s and sometimes 70s. He has never been down to the 50s.
Mr Cunliffe scored a respectable 16.8 per cent in his first appearance as Opposition leader in the preferred Prime Minister stakes.
His predecessor's rating in June was 12.4 per cent. A total of 20.4 per cent of those polled said they were more likely to vote Labour next election with Mr Cunliffe as leader than before, 14.4 per cent said less likely, and 63 per cent said it would make no difference to their vote.
JOHN KEY: POLL REFLECTS LABOUR LEADERSHIP COVERAGE
Mr Key said the poll was a snapshot in time, and reflected the focus there had been on Labour over recent weeks.
"Labour have had extensive coverage over the past six weeks as they've gone through their change of leadership. The polls move around a lot and I've always thought that the election in 2014 will be very tight. This poll indicates that."
He said closer to the election, people would start to look at the possible coalition options.
"Voters will start to look at what sort of Government they want to lead us beyond 2014.
What we do know with Labour is it will be a Government that will have to be formed with the Greens and given the public statements of David Cunliffe, it's going to be very much a far left Government on offer versus a centre-right government that has led New Zealand over the last five years."
He said he did not really have much to say about Mr Cunliffe's result in the first full poll under is leadership.
CUNLIFFE: POLL CAPS OFF GOOD FIRST WEEK
Mr Cunliffe said the poll result capped a good first week for Labour under his leadership.
"We've had the benefit of an open and transparent leadership race which has been conducted in good humour.
"The poll was taken after the results were announced, we got a clear mandate out of it, and the Labour team has come together very promptly and professionally around the leadership.
"And we've announced a reshuffle in a week flat."
Asked whether the poll vindicated the change in leadership, he said: "I don't know." But he added: "I have a style which is pretty up-front and direct, and I think people like to get direct answers to questions."
Mr Cunliffe said the increase in support for Labour reflected the fact that New Zealanders were concerned about the erosion of civil freedoms, in particular the spying reforms, and had concerns about economic growth and a widening inequality gap.
New Zealand First gained 4.4 per cent support in the poll, putting it below the 5 per cent threshold. This means that unless it won an electorate, it would have no seats.
Leader Winston Peters gained 6.2 per cent support as preferred prime minister.
National may see the poll result as the result of saturation attention on Labour but it also highlights one of National's biggest electoral problems - the lack of support partners.
The seat calculation figures assume - as have other polls - that electorate seats held by Act, United Future, Mana and the Maori Party are retained. But that is not nearly as certain as it has been for previous elections.
National has faced fewer controversies in recent months than it did at the start of the year, but the Opposition has been accusing it of "crony capitalism" over issues such as the $30 million payment to Pacific Aluminium Smelter, possible help for Chorus through internet pricing and the SkyCity convention centre deal.
National has passed the GCSB legislation, faced uproar over limits to snapper catches, and has made progress on its next part-sale of state-owned energy company Meridian.
The drop in National's support is also reflected in the poll question about whether the Government is moving in the right direction. The percentage answering "yes" dropped 5.5 points and the "no" response increased 5.9 points.
National 43.7 (down 5.1)
Labour 37.7 (up 6.8)
Green 11.3 (up 0.8)
NZ First 4.4 (down 0.7)
Maori Party 0.8 (down 1)
Mana Party 0.7 (up 0.2)
Act 01. ((down 0.1)
United Future 0 (down 0.3)
Conservatives 1 (down 0.5)
PREFERRED PRIME MINISTER
John Key 55.8 (down 9.4)
David Cunliffe 16.8 (up 14.6)
Winston Peters 6.2 (down 0.2)
Russel Norman 3.7 (up 0.1)
SEATS IN THE HOUSE
United Future 1
•Assumes that Mana, Maori Party, Act and United Future retain their electorate seats.
* The poll of 750 eligible voters was taken between September 17 and 23 and has a margin of error of plus or minus 3.6 per cent. The party vote result is of decided voters; 8.6 per cent of respondents were undecided.