A further 15 schools have signed up to join a coalition criticising the Government's review of NCEA.
The group of now 70 principals, dubbed the NCEA Coalition, have called for the review of NCEA to be halted.
They described the consultation process as "bizarre", putting the views of children ahead of professional educators and lacking proper consultation with school leaders and teachers.
Glen Denham, principal of West Auckland's Massey High School, said the coalition had made some progress over the past couple of days with some dialogue occurring behind the scenes with the Government.
"We are hopeful of some positive developments early next week. Until then, we will not be publicly commenting further."
The group took out a full-page advertisement in national Sunday newspapers to air its criticism.
Denham said the coalition would continue its campaign to alert parents to the dangers to their children's education under the current review process.
"What unites our 70 schools is our shared commitment to New Zealand's young people, and our professional judgment that the government's irregular NCEA review process will jeopardise their futures," he said.
Denham said other schools plan to make a decision in the next few days.
The 15 new coalition members in geographical order are:
1. Kingsway School, Hibiscus Coast
2. Saint Kentigern College, Auckland
3. Tauranga Boys' College
4. Hamilton Girls' High School
5. Hamilton Boys' High School
6. Gisborne Boys' High School
7. Hastings Boys' High School
8. Sacred Heart College, Napier
9. Hutt International Boys' School, Wellington
10. Rongotai College, Wellington
11. St Catherine's College, Wellington
12. St Patrick's College Silverstream, Wellington
13. St Margaret's College, Christchurch
14. St Andrew's College, Christchurch
15. Northern Southland College, Lumsden