The latest 3 News political poll shows the Labour Party is still struggling, with its party vote down 2.2 percentage points to 27.3.
The National Party is also down by 0.6 points, but still retains a wide margin with 49.7 percent and would be able to lead a government alone.
Labour's most likely ally in a future government - the Green Party - made the most gains in the 3 News-Reid Research poll, up 2.5 points to 12.7 percent.
That would give that bloc 40 percent of the party vote - well behind National's nearly 50 percent.
The other parties would not pass the 5 percent threshold to get them into Parliament.
New Zealand First is down two points to 3.6 percent, the Conservatives are up 0.5 to 2.8 percent, and Internet Mana has made its first showing with 1.8 percent.
Some 750 rather than the usual 1000 people were polled, with a margin of error of 3.6 percent.
During polling, Labour was still fighting off accusations it received undeclared donations from a Chinese millionaire businessman who has now changed his story, and while Prime Minister John Key was in the United States meeting President Barack Obama in Washington.
The general election will be held on 20 September.