The author of the book Dirty Politics, Nicky Hager, says John Key and the National Party still have questions to answer despite a resounding election victory.
Dirty Politics claims National ministers and staff repeatedly smeared opponents by feeding damaging information to right-wing bloggers.
That lead to the resignation of Judith Collins as a minister.
Mr Hager said he knew National was high in the polls and likely to win the election when he published the book.
But he said people will still be talking about the issues the book raises long after the election, because Mr Key still has not answered any of the questions it poses.