Failure of the Greens to return to Parliament would be hugely significant, following their slide to below the five per cent threshold in the latest 1 NEWS Colmar Brunton poll, says 1 NEWS political editor Corin Dann.
The Greens slumped 11 points from 15 per cent to 4.3 per cent, the party's worst result since September 2009.
The poll was taken over the last five days, capturing the fallout from the Greens' meltdown after former leader Metiria Turei's benefit fraud admission, and the so-called "Jacinda effect" of Labour's new leader.
National slipped back three points in the poll to 44 per cent, its lowest level in four years, while Labour soared 13 to 37 per cent, its highest since 2008. New Zealand First were down one per cent at 10.
Corin Dann says the whole proportionality of Parliament would be affected by the Greens not making it back.
He said the four per cent of Greens votes could be "wasted" and that makes it slightly easier for the largest party, National, to get across the line.
Dann says at the same time the poll, he thinks, increases the likelihood of a change of government because it makes Winston Peters perhaps more favourable towards going with Labour.
That's because the New Zealand First leader "doesn't have to worry about the Greens as the third party. It's not the three-way deal, if you like, that had been proposed".
For now, the momentum is with Labour and National will be "absolutely" worried about this, Dann said.
National has been letting the Jacinda effect run for a little bit he said.
"They've come out hard with policies. But do they now have to change tack? Do they have to think of trying to perhaps go a little bit negative here? Because what they've got to do is stop momentum because there is a roll on with Labour. And what they will be worried about is that they can't stop it in five weeks," our political editor said.
The poll had the Maori Party up one to two per cent and The Opportunities Party steady at two.
In the preferred prime minister stakes, Jacinda Ardern has surged 24 points to 30 per cent to be neck and neck with Bill English who's up two to 30.