A school trustee says school boards are under pressure from principals and teachers to join a revolt against the national standards in reading, writing and maths.
But trustee groups are also providing their own advice to boards about the standards and their obligations.
The School Trustees Association says it does not know how many more schools might join the more than 240 that on Wednesday announced their opposition to the standards.
But the chairperson of its Waikato region, April Tauelangi, doubts the number in her area will grow much beyond the 30 that have already signed up to it.
However, she says boards are under pressure from principals and teachers to oppose the standards.
She says about 60% of trustees are new to the role so principals and teachers have a better opportunity to win them over.
Union doubts sanctions will work
The primary teachers' union is dismissing possible Government sanctions against schools that oppose the national standards.
Official documents show ministry actions over the schools' opposition start with advice and support, rising to reviews by the Education Review Office and denial of access to professional development.
The final interventions are appointing statutory managers and replacing boards with commissioners, but NZEI president Frances Nelson says the ministry is unlikely to be able to find enough people for those roles if the number of schools in opposition grows.
The union also says the possible sanctions are so punitive they could encourage more boards to oppose the national standards.