Voters are rejecting a return to old-fashioned single-party government and say they prefer coalition rule.

The finding in the latest Fairfax Media-Research International poll comes as Prime Minister John Key plays one of his biggest cards in the final week of the campaign by appealing to voters to back National rather than let the incoming government be held hostage to New Zealand First.

On today's poll, NZ First is just one point away from making an historic return to Parliament.

With National currently polling at above 50 per cent support there appears to be little chance of NZ First leader Winston Peters holding the balance of power but that could change if there is a sudden slide in National's support in the final days of the campaign.

Mr Key has used the spectre of NZ First's return to galvanise National supporters into voting on Saturday by warning it could spell instability and uncertainty as the world economy faces more volatility.

He has warned that any deal Labour might be capable of stitching up after the election is inherently unstable because it would rely on Labour reaching separate agreements with the Greens, NZ First, the Mana Party and potentially the Maori Party.

The attack on NZ First is mostly an attempt to combat apathy among National supporters – but it could also be read as a coded message to voters to give National the support it needs to govern alone. Mr Key has avoided stating that outright, however – and the latest Fairfax Media-Research International poll suggests that such a prospect would not be favoured by most voters.

The poll of 1000 voters shows that a majority prefer coalition government, at 54.1 per cent of those questioned. Just under 40 per cent of voters would prefer one party to govern alone.

Mr Key has repeatedly said that he will do deals with minor parties ACT, the Maori Party and – "tangentially" – the Greens, even if National does not require their support to govern.

But our poll suggests National voters are less likely to be turned off by the prospect of the next government having "unbridled power" – the poll is split on party lines, with 61.7 per cent of National supporters preferring one-party government compared with 33.6 per cent of Labour supporters.

That is probably because National is in with a chance of governing alone on current polls, but Labour is not.

There is also a clear split by age – younger voters are much also less likely to support single-party government.

-Fairfax NZ