Efforts were expected to continue today to break the deadlock between the Education and Library Boards and classroom assistants threatening to strike tomorrow.
Emergency talks between the groups failed last night with representatives of public service union Nipsa saying it appeared as though the Boards were not in a position to meet their demands.
It is not known yet how many schools will be affected by the proposed walk out. Some may be forced to close early, while children with special needs may be required to remain at home.
Meanwhile, the Education Minister has come under fire for her attempt to avert strike action by thousands of Ulster classroom assistants.
Less than two days before classroom assistants stage a one day walk out, Caitriona Ruane told the Assembly that she will intervene in the situation - the latest twist in the longest ever running pay dispute in the province.
However, union representatives hit out angrily at what they regard as her suggestion that their members should accept an offer they have already refused.
Brian Booth, NIPSA branch secretary and classroom workers strike committee member, said: "By doing what she has done she has sharpened the issue. She has brought about a situation where there will no doubt be conflict between the members, Education Boards and her Department.
"We are absolutely disgusted with her attitude. Caitriona Ruane's statement is rhetoric without real meaning. She is going to implement what every classroom assistant across Northern Ireland rejected in June."
If no resolution is found, classroom assistants will walk out for three days, beginning on October 2, with all-out strike action commencing on October 8.
Speaking yesterday, Ms Ruane maintained that she wanted a resolution which will serve both classroom assistants and pupils.
"I have decided that to make progress, I am going to intervene. I am now calling on the employing authorities to proceed as swiftly as possible to implement the new gradings so that these valuable staff receive the pay rates to which they are entitled as a result of the systematic job evaluation process which has been carried out."