Charter school opponents have released a survey showing an overwhelming majority of parents don't think they should be allowed to hire unqualified teachers.
The government on Thursday published details of how the schools will be run, showing they will be able to hire registered and unregistered teachers.
That's caused an outcry from opposition parties and on Friday the primary teachers union NZEI released an opinion poll which questioned 1000 parents.
It showed 86 per cent believed the schools shouldn't be allowed to employ unqualified teachers, and 60 per cent thought there was "a real risk" that if they were run by private companies profit would take precedence over education.
The schools can be run by community, business or religious organisations and will be state funded.
NZEI national president Ian Leckie says the government is taking "a huge risk" by launching what the union considers is an assault on professional teaching.
"Our children shouldn't be used a guinea pigs in dangerous experiments led by ideology simply to uphold the ACT Party's support for the National-led government," he said.
Charter schools are an ACT initiative and setting them up is a commitment in the party's support agreement with the government.
ACT leader John Banks is defending the use of unregistered teachers.
"This new model allows for a proportion of the staff not to be registered as a teacher," he said on Friday.
"This is not the same as not being qualified... there are already early childhood educators, volunteers, tertiary educators and staff at private training establishment who are teaching but are not registered."
Mr Banks says charter schools will be better suited to teach children who are failing in state schools.
"They are simply another choice for parents and learners."