The author of a book about the life of John Key has admitted the timing is "manna from heaven" for the National Party campaign.
But journalist John Roughan claims the biography - John Key, Portrait of a Prime Minister - won't influence the election campaign.
"He (John Key) doesn't need this book, he's up at 50% in the poll...he could hardly be more popular and he probably won't be come election time so I don't think it'll make much difference," Mr Roughan says.
The senior columnist for the New Zealand Herald says while the book may be beneficial, that was not driven by Mr Key or his party.
Mr Roughan said the project both excited him and filled him with fear. He told TV ONE's Breakfast he was surprised at how much Mr Key "lives life on the edge".
The biography is unauthorised, meaning Mr Key wasn't allowed to read it until it had gone to print, and wasn't able to veto any of the copy.
The Prime Minister says he had no influence on the book other than what he said in the interviews.
"At the end of the day the way I kind of look at that is you take risks when you do these things and I was for him to write the story," Mr Key says.
But Claire Robinson from Massey University says people will critique the book for its timing and the fact that it's probably overly positive.
"In the long term it's only going to be good for him," Professor Robinson says.