Two days out from Saturday's general election, National Party leader Don Brash has become favourite to win, according to online bookmaker Centrebet.
Centrebet's prime minister odds favour Dr Brash for the first time since July 26. He has been Centrebet's PM underdog for all bar one day of the officialcampaign to date.
But this week punters have wagered more than $150,000 on Dr Brash to lift him to favouritism.
Labour's outlook is so bleak that some punters are changing horses and accepting losses.
"You know that you're in trouble when punters who backed your party at short odds several weeks ago switch sides and lock in an election betting loss," said Centrebet's Gerard Daffy.
Austalia-based Centrebet specialises in election betting and it claims that its odds are more accurate than polls.
Stanford University researcher Justin Wolfers and Andrew Leigh, of Harvard, found that Centrebet's odds on the 2001 Australian federal election not only forecast the overall result correctly but also provided precise estimates of outcomes in more than 40 electorates.
Dr Brash is paying $1.80 to win, while Labour leader Helen Clark is at $1.90.
