If the poll translated to seats in Parliament, New Zealand First leader Winston Peters would hold the balance of power on 8.1 per cent or 10 seats.
Sixty-two seats would be needed in a 122-seat Parliament, and the poll results would translate to 55 for National, 39 for Labour and 14 for the Green Party.
With the support of the Maori Party, Act and United Future, National would get to 59 seats.
Speaking this afternoon, Key said people had spoken of Peters as a king-maker in the lead-up to recent elections, but that had not transpired.
"Maybe we will need to rely on some parties more than others. We are still quite a way from an election and there is a fair bit of water to flow under the bridge."
Despite the poll gain by Labour, Key said he wasn't worried.
"We know every election is going to be tight - they have been the whole way through. If we could poll that number on election night 2017 we would probably be the Government."
In the preferred prime minister polling, Key was unchanged on 36.7 per cent.
Winston Peters fell 1.2 per cent to 10.9 per cent, with Little jumping 1.6 per cent to hit double-figures at 10.5 per cent.
Asked if the Government was doing enough to control the housing market, 75 per cent of respondents said "no", a drop of 1.4 per cent since the last poll in May. Twenty-two per cent thought enough was being done, up 2.5 per cent.
The poll of 1000 people was taken between July 22 and August 3 and has a margin of error of 3.1 per cent.
Where they stand
Newshub/Reid Research poll:
• National 45.1% (down 1.9%)
• Labour 32.7% (up 1.4%)
• Green Party 11.5% (up 0.4%)
• NZ First 8.1% (up 0.3%)
• Maori Party 1.3% (0.3%)
• Act Party 0.2% (down 0.2%)
• United Future 0.1% (up 0.1%)
