New Zealand First is on the rise and seems assured of returning to Parliament in bigger numbers, according to the latest Herald-DigiPoll survey.
And Labour appears to have arrested its steady decline.
National has dropped below 50 per cent for the first time in DigiPoll surveys this year and would need partners to govern. With eight days to go to the election, it could turn out to be a tighter race than the past few weeks have suggested.
Watch: Key: 'It's a clear choice'
"It just shows you how tight the race is going to be, " Prime Minister John Key said last night.
New Zealand First is on 8.1 per cent, up by two points. That would bring in 10 MPs including former MP Ron Mark. That's two more MPs than it got in the last election.
New Zealand First would not hold the balance of power under this poll scenario because National could form a bare majority with just one of its support partners (Act, United Future or the Maori Party) or a comfortable one with all three of them, assuming they are returned.
Labour is up slightly to 24.6 per cent. It is the first time in the past six DigiPoll surveys that it has not declined. However, Labour would not be able to form a Government even if it combined with the Greens, New Zealand First, Internet-Mana and the Maori Party.
Their combined vote would be 59 when a majority in a 122-seat Parliament would be 62.
The Conservatives are unchanged on 3.8 per cent and would not make it into Parliament.
Internet-Mana is down by 1.2 points to 2.3 per cent, possibly a reflection of talk of tensions in the alliance, although this result would see Laila Harre and Annette Sykes elected as long as leader Hone Harawira keeps his seat.
The biggest movement has been in the preferred PM ratings.
The popularity of Mr Key has fallen by 7.3 points to 61.6 per cent, his second lowest rating since becoming Prime Minister in 2008. The popularity of Labour leader David Cunliffe is up by 3.9 points to 17.9 per cent and New Zealand First leader Winston Peters is up by 1.4 to 7.8 per cent.
Mr Key's advice to voters was not to try to second-guess the polls and if they wanted a National-led Government, to vote for National.
Polling began on Thursday last week in relatively clean air - six days after Judith Collins resigned from the Cabinet. An inquiry will determine whether Ms Collins sought to undermine former Serious Fraud Office head Adam Feeley while she was Minister of Justice, as suggested in an email from Whale Oil blogger Cameron Slater. Since her resignation, there has been far less coverage of the Dirty Politics book that was denying oxygen to Opposition parties in the election campaign.
The party vote: National 48.6 (down 1.5), Labour 24.6 (up 0.8), Green 11.5 (up 0.1), NZ First 8.1 (up 2.1), Conservatives 3.8 (no change), Internet-Mana 2.3 (down 1.2), Maori Party 0.7 (up 0.3), Act 0.3 (down 0.1), United Future 0 (down 0.3), Legalise Cannabis 0 (down 0.1).
• The poll of 750 eligible voters was conducted between September 4 and 10. The party vote is of decided voters only. Undecided voters were 9.1 per cent. The margin of error is 3.6 per cent.
Where they stand
Labour has the support of 21.2 per cent of men for the party vote, compared to 18.4 per cent last week, according to a breakdown of the latest Herald-DigiPoll survey.
Labour's support among women is 27.8 per cent this week, compared to 28.9 per cent last week.
In the preferred Prime Minister stakes, Prime Minister John Key had 74.8 per cent of men supporting him last week. This week 65.4 per cent of men support him. Last week, 11.9 per cent of men supported David Cunliffe. This week, 17.1 per cent support him. Winston Peters last week had the support of 5 per cent of men. This week, he has the support of 8.5 per cent of men.
Major events during the polling period include two televised small-party leaders' debates and the Press debate between Mr Cunliffe and Mr Key.