The first poll since the Jami-Lee Ross saga shows National has dropped below Labour, and Judith Collins is breathing down Simon Bridges' neck.

National dropped two points to 43 per cent while Labour surged ahead three points to 45 per cent in Tuesday's One News/Colmar Brunton poll. The Greens were up one to 7 per cent while NZ First were steady on 5 per cent, and ACT were too low to register.

The poll was released on Tuesday night and takes in the period from Monday to Friday last week.

This is the first poll since Jami-Lee Ross resigned from the National Party in spectacular fashion, alleging electoral fraud on the behalf of leader Simon Bridges and releasing a politically damaging secretly recorded conversation with Bridges.

It is also the first poll since the event that sparked that controversy - the leaking of Bridges' expense details to Newshub. There has not been a major poll since early August - before the Clare Curran/Derek Handley saga and Meka Whaitiri allegations were completed.

STUFF The first poll since the Jami-Lee Ross saga brought bad news for National.

Bridges' preferred PM ratings were down three points to 7 per cent while Prime Minister Jacinda Ardern was up two to her highest ever rating - 42 per cent.

Notably, National MP and former leadership opponent to Bridges Judith Collins was at 5 per cent in the preferred PM rankings, while NZ First Winston Peters was on 4 percent. This is not Collins' first time in the preferred PM poll - she has been at 2 per cent for much of the year.

Bridges told One News it had been the "toughest, worst week in living memory for National and I think for any leader" and he would be moving quickly to get back talking about what mattered to voters.

On these numbers Labour would have 54 seats and could govern with just the Green Party and their 8 seats, taking it beyond the 61-seat threshold. NZ First could also bring its 6 seats into that majority but it would not be needed and Labour could not govern with just NZ First.

National would have 53 seats, and would be well away from governing - even with ACT's presumed 1 seat in Epsom, or with ACT and NZ First.

The poll asked 1006 eligible voters by both mobile phone and landline and had a margin of error of 3.1 per cent.