A Fairfax Media-Research International Poll released today showed Labour in trouble at 29 percent, while National sat on 56 percent - enough support to govern alone should the poll be replicated in the November 26 general election.
The results were in line with other recent polls.
On July 17, a TVNZ Colmar Brunton poll put support for Labour at 27 percent - down 7 percentage points from its previous poll in May - while National was up one point on 53 percent.
A week earlier, a TV3 Reid Research poll had National at 55.1 percent and Labour at 29.9.
Deputy Labour leader Annette King responded to the latest poll today, using the words of former Prime Minister Jim Bolger, who memorably said "bugger the pollsters" on election night in 1993 when National won by one seat after polls predicted a landslide victory for it.
"I couldn't do any better than to quote Jim Bolger and say 'bugger the polls'," Ms King told reporters this afternoon.
"What we feel on the ground and what people say to us isn't reflected in the poll."
Ms King said the party had a lot of policy to release before the election.
"People start to concentrate on what parties have to offer much closer to the election," she said.
"Some of us have been around long enough to know that a poll on the day is a poll on the day. The one that's really going to matter is the one on election day."
Today's poll also showed greater loyalty among the National voters, with 92 percent of those who said they would vote for the party having voted the same way in 2008.
By contrast, Labour only retained 79 percent of its 2008 support, losing 11 percent of last election's votes to National and 5 percent to the Greens.
The Green Party was the only minor party to pass the 5 percent threshold. ACT and NZ First each achieved 2 percent, while United Future, Mana and the Maori Party all scored 1 percent support or less. Under MMP, parties need 5 percent of the vote to win seats in Parliament if they do not win an electorate.
The majority of National voters preferred ACT as a coalition partner, while the majority of Labour voters preferred a Green Party coalition. No poll participant favoured a coalition with Mana.
The poll was conducted while Prime Minister John Key was receiving positive coverage of his United States trip, during which he met President Barack Obama.
Mr Key recorded 53 percent support as preferred prime minister, compared to Labour leader Phil Goff's 6 percent.
The poll was conducted between July 21 and 25, and surveyed 1004 eligible voters. It has a margin of error of 3.1 percentage