New Zealand First has more than doubled its support in the latest Herald-DigiPoll survey and its leader, Winston Peters, has gained popularity as preferred Prime Minister.
Mr Peters last night called it "the beginning of a sea change".
He has not yet regained enough support to give him and his party the balance of power as they held in 1996.
But the party on the rise has enough support to put it into coalition contention.
If the poll result were translated to seats, New Zealand First would be an alternative to the Greens if a Labour-Progressives partnership wanted to limit itself to one coalition partner.
New Zealand First has jumped from 3.6 points in last month’s poll to 7.3 per cent and Mr Peters is preferred Prime Minister by 10.9 per cent, up 2.9 points.
Mr Peters has kept a low profile during the two-week parliamentary recess that ends tomorrow but before that received a higher level of exposure over his renewed courtship of the grey vote, and in his advocacy for the Berrymans.
He is expected to receive more attention when Parliament resumes tomorrow with further allegations that one of Saddam Hussein’s former ministers is living in New Zealand and on Wednesday when his private member’s bill abolishing Treaty of Waitangi clauses in legislation gets its first vote in the House.
The second largest movement is in Labour’s results, with its party support down three points to 44.7 per cent.
And while Helen Clark’s ratings as preferred PM have fallen by 5.7 points, at 56 per cent, she is still more than double her nearest rival, National leader Don Brash, who has slightly improved to 23.9 per cent.
National has fallen slightly, by 1.2 points to 33.2 per cent, but because Labour has fallen by more, the gap between National and Labour has reduced to 11.5 points.
It was 13.2 points in last month’s poll.
The narrowing of the gap will be only of slight comfort to National, however - with an election scheduled to be held within the next 21 weeks, an 11-point gap is very large, particularly when the trend of previous MMP elections has been for the larger parties to lose support and smaller parties to gain.
The Greens are on 5.8 per cent (up 0.7); United Future 3.1 ( up 1.2); Act 2.2 per cent (no change); Maori Party 2.1 per cent (-0.1); and Progressives 0.3.
The present Labour-Progressives minority Government relies on the support of United Future on confidence and supply issues.
If translated to seats, United Future would not have enough seats to make that possible.
A Labour-Progressives minority would have to do a deal with either the Greens or New Zealand First to win on outright majority.
The Parliament - assuming United Future leader Peter Dunne wins his electorate seat, Maori Party leader Tariana Turia wins hers, Progressives leader Jim Anderton wins his; and that Act does not win an electorate seat - would comprise the following seats: Labour 56, National 41, New Zealand First 9, Greens 7, Maori Party 3, United Future 4, Progressives 1.
Under the scenario outlined, Act would not be in the next Parliament because it received less than 5 per cent and did not win an electorate seat. Parliament would be increased to 121 MPs because the Progressives won one seat (Mr Anderton’s Wigram one) more than entitled to by the party vote.
A majority would be 61.
Mr Peters said it was a difficult poll to interpret but his party had completed its election planning and was ready to go.
Asked if he believed his party could again hold the balance of power, he said: "We don’t use that phrase. We’ve moved on from there."
* The survey of 800 respondents was conducted between April 22 and 29 and the political party and preferred Prime Minister polls were of decided voters only.
It has a margin of error of plus or minus 3.5 per cent.