The poll also found that Mr Peters would win easily, with 51 per cent to Mr Osborne's 37 per cent, if Mrs Prime were to pull out of the race. The Q&A poll had a sample size of 1000 people, double the size of the 3News poll.
Playing into Mr Peters' hands are perceptions - real or imagined - that National's easy run in the past has allowed the party to take Northland votes for granted, as well unanswered questions about Mr Sabin's resignation.
The 3News poll appears to have spurred National into action. The region has been awash with Government ministers and yesterday National pledged to spend up to $69 million replacing 10 one-lane bridges around Northland, including the unloved bridges at Whangaroa, Taipa and Rangiahua.
Sunday's poll, however, also puts Labour in a difficult position. It is too late to withdraw Mrs Prime's nomination but party leader Andrew Little has urged supporters to "think carefully about how they exercise their vote" if they wanted to send a message to the National-led Government.
On the hustings in Kerikeri on Sunday Mrs Prime said she had no plans to ease up on her campaign, and that she believed she was still the best person for the job.
Losing the Northland seat would not have a drastic effect on National's ability to govern but would make the party more dependent on United Future or the Maori Party to pass legislation. It could also stymie National's plan to overhaul the RMA, which is backed only by Act.
The by-election, which is expected to cost taxpayers close to $1 million, is due to be held on March 28.
The last time National lost Northland was in 1966 when Social Credit's Vernon Cracknell won what was then called the Hobson electorate.
The other candidates are Adrian Paul Bonner (independent), Joe Carr (Focus NZ), Robin Grieve (ACT), Maki Herbert (Aotearoa Legalise Cannabis Party), Adam Holland (independent), Rob Painting (Climate Party), Rueben Taipari Porter (Mana) and Bruce Rogan (independent).
- More election coverage on p3 and p8.