Primary and intermediate school principals say their refusal to cooperate with the Education Ministry is putting the ministry under pressure.
Educational Institute members started the boycott in July over their stalled pay talks and will decide next week whether to extend it to the middle of October.
The union says the ministry is already being forced to cancel meetings because of the action and an extension would seriously hamper government plans to overhaul the school system.
RNZ education correspondent John Gerritsen has the story.
