The Green Party would boost its numbers from nine to 13 MPs if the latest weekly Herald DigiPoll survey was translated to votes.
With the retirement of current MPs, six new faces would join the seven incumbents.
The Greens have risen slightly to 10.1 per cent, the highest the party has been in the DigiPoll survey since the election campaign in 2002 when it peaked at 11.3 per cent - though it gained only 7 per cent in the election.
The Greens have yet to start their campaign. The official launch will be in Wellington on Sunday but today the party will release its conservation policy.
On the latest result, Labour would lose seven MPs, National would gain nine and the Greens would gain four extra MPs.
The calculations are based on the assumption that United Future, Act and Mana retain one electorate seat and the Maori Party keeps four.
Labour's early momentum in the election campaign has not translated to an early lift in support. It has fallen below 30 per cent to 29.1 - the first time it has been in the 20s in the DigiPoll survey.
Keeping above the 20s has been an unstated ambition of the party's.
It wants to avoid any comparisons with 2002 when the National opposition was wiped out against a highly popular party and Prime Minister seeking a second term.
The party opted not to have a formal campaign launch like National did on Sunday and it has decided not to put the face of leader Phil Goff on its billboards.
Nonetheless, Mr Goff began the campaign strongly with KiwiSaver and superannuation savings policies and a credible performance in the first of the two big debates with Prime Minister John Key.
The polling period does not cover the period of The Press debate in Christchurch where Mr Key challenged him about holes in Labour's spending and borrowing plans.
National is up fractionally to 54.2 per cent, enough to govern on its own with 67 seats.
No other party reaches 2 per cent in the party vote but the Colin Craig-led Conservative Party has featured in party vote ratings for the first time, with 1 per cent. That is higher than Act on 0.9 per cent, United Future on 0.5 and Mana on 0.1.
Mr Craig is standing in the Rodney electorate, held by National.
The combined total of Labour, the Greens, the Maori Party and Mana would be 54.
The poll also suggests there could be a lot more soft support for the Greens to tap.
In a special question on the Greens, 18.6 per cent agreed with the statement that the party keeps others honest and they would vote for them; 65.6 per cent agreed the Greens are good to have around but they probably wouldn't vote for them; and only 12.8 agreed with the statement that the Greens moan too much about New Zealand environmental standards.
The poll also shows that most voters trust New Zealand politicians to keep their promises, with 64 per cent giving them a rating of 50 per cent or higher and 34 per cent rating them lower than that.
Asked how they would rate their level of trust in politicians to keeps their promises, 12 per cent rated them at 75 to 100 per cent; 52 per cent rated them at 50 to 74 per cent; 25.4 per cent rated them at 25 to 49 per cent; and 8.6 per cent rated them at 1 to 14 per cent.
Mr Key is preferred Prime Minister on 70.6 per cent, the same as last week, and support for Labour leader Phil Goff has slipped from 13.7 per cent last week to 11.7 per cent this week.
New Zealand First leader Winston Peters is on 3.7 per cent but his party support has slipped from 2.8 per cent to 1.7 per cent.
The poll of 750 voters was conducted between October 28 and November 2 and has a margin of error of plus or minus 3.6 per cent. The party votes are of decided voters only and 10.3 per cent of respondents were undecided.