Teachers are threatening to pull the plug on a move to allow pupils in almost half of second-level schools to be given an alternative to religion classes.
It affects about 350 community and comprehensive schools and community colleges, where the State is involved in the patronage, and reflects a growing recognition of the rights of students not to participate in religion classes.
Education Minister Richard Bruton announced last month that, from September, students in these schools who don't want to sit through religious instruction must be timetabled for another subject.
But he didn't consult with schools or unions, and management bodies reacted immediately saying that they don't have the resources to ensure that students can be provided with alternative tuition.
Teachers, whose union annual conferences this week heard much about lack of resources in schools, are similarly infuriated and, today, delegates at the Teachers Union of Ireland (TUI) conference are expected to support an emergency motion banning co-operation unless supports are put in place.
TUI president Joanne Irwin told Mr Bruton yesterday that the directive to schools "came out of nowhere" and offered no additional resourcing for its implementation.
"You are expecting schools to offer 'alternative tuition', meaning subjects to students at the time that religion instruction takes place. How can this be done?"
She said she had no doubt that the outcome of the debate on today's motion, which has been signed by 20 union branches, will be to direct members not to comply with the Department of Education circular.
The motion complains that the resources required for the implementation of the circular "have not even been quantified, let alone supplied".
Ms Irwin said they had "no intention of infringing the constitutional rights of students and their parents and will not do so, but to ask us to draw water with a colander from a dry well is to ask for the miraculous".
Parents have a constitutional right to withdraw children from religious instruction classes and activities, but practice around what those pupils do instead has been loose. Often they sit through the class.