Key: Huge task to win Mt Albert

Prime Minister John Key agrees National has a huge task to win the Mt Albert by-election, as it enters the last week of the campaign.

A TV One poll had Mr Shearer on 59 per cent support with National's Melissa Lee on 21 per cent.

The Green Party candidate, co-leader Russel Norman, was on 15 per cent, while ACT's John Boscawen barely registered with 3 per cent.

Mr Key told journalists internal National party polling had shown a similar picture, though that work had been done some time ago.

National had always faced an uphill struggle to take the Labour seat, but would continue to campaign hard, Mr Key said.

Saturday's by-election will fill the vacancy left by former prime minister Helen Clark - Mt Albert has been a Labour seat for 63 years.

Miss Clark held it at last year's general election with a huge majority of more than 10,000, although the party vote was much closer between Labour and National.

The poll showed a similar trend. When voters were asked which party they would support in a general election, 48 per cent said Labour and 37 per cent backed National.

There is only the candidate vote in the by-election.

The poll, which questioned 500 voters and had a margin of error of plus or minus 4.4 per cent, showed there could be a close race for second, if Dr Norman can increase his support during the next few days.

National never expected to win the seat but it would be an unexpected blow if it came third.

- NZPA