The Irish National Teachers' Organisation is to escalate its campaign for smaller classes in primary schools by making class size a key issue in the run-up to the next election.
The union plans to hold meetings in every school and every constituency in the State to raise public awareness of what it calls the range of "broken promises" on the issue.
The union said commitments in the Programme for Government to bring down class sizes for children aged under nine to below 20 were being ignored.
Public representatives will be invited to the meetings in over 3,000 schools. The union said it was seeking the support of parents and school management to lobby every public representative.
The INTO general secretary John Carr said classes of 30 and more pupils are still common, despite a series of Government commitments to reduce class size. He said the Government's failure to reduce class sizes was having a negative effect on pupils.
"We have a new, modern curriculum that was based on world-wide best practice. But without class size reductions, we are only scratching at the surface in terms of delivery - the full potential of the primary school curriculum cannot be achieved."
Mr Carr acknowledged that there are now extra teachers for special-needs children in schools. "But for every half an hour of resource teaching that a special-needs child gets, he or she spends five hours in some of the largest class sizes in Europe," he said.
"For one-tenth of the school day, the child gets proper support. For the other nine-tenths, the special-needs child is competing for teacher time and attention with up to 30 other children.
"It's time that we exposed the myth that inclusion and integration are possible in such circumstances and explain to parents, at national and local level, that inclusion and integration are illusions in large classes."
The issue of class size is set to dominate an education conference hosted by the INTO later today.
Minister for Education Mary Hanafin will address a major conference on civic, social and political education at the Institute of Technology in Tallaght, Dublin, this morning.