Support for National has slumped while support for the Greens has reached a record high, according to a new poll.
National would likely be able to form another government, according to today's Roy Morgan Poll, but a Labour-Greens coalition would also have a shot if it could attract support partners.
The poll shows support for National fell 4.5 per cent, to 44 per cent, while support for Labour rose 0.5 per cent, to 30.5 per cent.
The Greens picked up 4.5 per cent, boosting its support to a record high of 17 per cent.
Support for the Maori Party rose 0.5. to 1.5 per cent, while support for New Zealand First was unchanged on five per cent.
Support for the Mana, Act and United Future parties was also unchanged on 0.5 per cent each.
Roy Morgan executive chairman Gary Morgan said it was the first time since the 2008 election that support for the Labour and Green parties (47.5 per cent) was greater than support for National (44 per cent).
"Today's result shows that while National continues to enjoy a strong lead by itself, a combination of left-leaning parties could form Government if there was a shock election in the near future.''
Mr Morgan said the Greens had surged to their highest ever level of support.
"The record Greens' support coincides with the yearly `Earth Hour' which was held during the survey period last Saturday.''
The phone survey of 948 eligible voters was conducted from March 12 to April 1 - after news of the ACC scandal broke, leading to the resignation of senior minister Nick Smith.
"Recent controversies involving several National MPs have embarrassed the Government and provided plenty of `ammunition' for the Opposition,'' Mr Morgan said.