NZ First leader Winston Peters was still ahead of him on 11 per cent and Key remained strong on 38 per cent - down one since June.
The result will disappoint Labour which believed it was making ground against National by targeting the Government's handling of issues such as homelessness and housing affordability.
On the results, Labour would not be able to form a Government even with both the Greens and NZ First, both of which picked up some support.
The Green Party moved from 12 to 13 per cent which would give it 15 MPs in Parliament.
NZ First went up two points to 11 per cent - within a whisker of overtaking the Green Party.
However, it would not be the kingmaker on those results - National would be able to form a Government with its current support parties.
Although Little has claimed Labour's internal polls have the party in better shape the result in the long-running Colmar Brunton poll will concern Labour MPs and gives Little very little room for mistakes in the future.
After a caucus meeting tomorrow, Little is travelling to Canada to attend the Global Progress conference, an international gathering of social democrat party leaders where he will rub shoulders with the likes of Canada's PM Justin Trudeau.
While that might invite jokes about coups while a leader is overseas, there is little appetite for another leadership change in Labour.
It is the first full poll by Colmar Brunton since Labour and the Green Party signed an agreement to work together more closely.
The Maori Party also had a small lift from one per cent to two per cent - possibly a reflection of talks between the party's new President Tuku Morgan and Mana leader Hone Harawira as well as an apparent endorsement from the Maori King.
The poll of just over 1000 voters has a margin of error of +/- 3.1 per cent and was taken from 3-7 September.