Teachers would only have to deliver one period of substitution each week and they would not be required to be on call on any day, according to a deal worked out by the ASTI with school managers earlier this week.
However the document was rejected by the ASTI standing committee or executive on Wednesday. The committee voted to reballot members on the Department of Education's €37 an hour.
Last night, education sources said the document "went a very long way to meet ASTI's demands". However, one leading ASTI figure said the compromise was rejected on the basis that teachers would still have to designate two periods of their timetable for substitution.
A date has still to be fixed for the new ballot. There is already concern in the ASTI that the turnout could be low as this is only the latest in a series of ballots in the past two years. It is widely expected that the union will reject the supervision arrangements.
Its general secretary, Mr Charlie Lennon, claimed on Morning Ireland yesterday the union had been "sold a pup" by the Department and the school management bodies before it voted to accept the deal by a 60-40 margin in the original ballot in November.
Some teachers blame the leadership for the confusion. The union leadership and executive members are now bracing themselves for strong criticism from ordinary members during the ballot.
At the heart of the dispute is whether teachers would be paid for being available for substitution as the ASTI demands. The management bodies want a system which is based on the delivery of the actual work.
The ASTI is concerned that members would not be paid for being on call and that members could be obliged to deliver two periods of substitution per week.
The compromise document agreed between ASTI leaders and the management bodies appeared to open the way for a deal but it was rejected by the ASTI executive. On substitution the document states that teachers "may be rostered for two periods of substitution per week but will only be required to deliver one because of the commitment to supervision and the overall limitation of one and half hours per week prevents such teachers from being obliged to deliver a second period in the week. It also prevents roll over of delivery of the commitment from one week to another."
The document continues: "Teachers will be advised at the start of the school day whether they will be required for their rota periods (of substitution) for that day and therefore, teachers will not be required to be on call on any day."
The Minister for Education, Mr Dempsey, is known to be furious with the ASTI move. The Department takes the view that the union has "voted against itself and in a way which makes no sense", as one source put it.