ASTI, the Union representing secondary school teachers, has received a vote of no confidence from eight of its branches.
The revolt was sparked after ASTI bosses refused to allow members vote on the Government’s £27 an hour offer for supervision and substitution.
Branches in Kerry, Dublin and Waterford have questioned the Union’s leadership, while a further 56 branches have supported motions which are critical of the General Secretary, President, Central Executive and the Standing Committee.