The National Party has soared in popularity while Labour has plummeted, a new poll on the eve of the election shows.

NZ First has also fallen in the latest One News Colmar Brunton poll and is dangerously close to falling below the 5 per cent threshold.

In a complete reversal of momentum from the previous poll, National has arrested its fall and instead risen six points to 46 per cent. Labour is down seven points to 37 per cent.

Under the latest poll, NZ First is back to holding the balance of power, but only by the skin of its teeth.

New Zealand First has fallen 1 point to 5 per cent. If the party fell any further, it would need leader Winston Peters to retain the Northland seat to remain in Parliament.

National and its support partners Act and the Maori Party would not be able to form a Government, and would need NZ First to get over the line.

The Greens have risen 1 point to 8 per cent, meaning that the left-bloc of Labour and the Greens have 45 per cent. A coalition with NZ First would get them a majority, but only just.

In more bad news for Labour, leader Jacinda Ardern has fallen in the preferred Prime Minister poll. She is down 3 points to 31 per cent.

National leader Bill English, on the other hand, rose five points to 37 per cent.

The Opportunities Party is steady on 2 per cent, and the Maori Party remains on 1 per cent. Act is on 0.3 per cent.

The 1 News Colmar Brunton poll has now lined up with the Newshub Reid Research poll, which has National holding a 10-point lead over Labour.

In the leadup to the polling period, Labour made a U-turn on its tax policy after sustained attacks from National on its "vague" plans.

Labour leader Jacinda Ardern said her party would delay any tax changes on property until after the 2020 election, rather than introducing them in the next term.

National leader Bill English has come under pressure over the fuel crisis in Auckland, which was caused by an oil pipeline being severed and led to domestic and international flights being cancelled.

Opposition parties have used the incident to attack National on its management, and its failure to put in place crucial infrastructure.

Under the latest One News poll, NZ First's Shane Jones would not get back into Parliament.