Another dispute involving the Educational Institute of Scotland and South Lanarkshire will not help the union's mood.
Teachers on the local joint consultative committee are threatening to pull out of all committees and working parties unless the council comes up with a deal on allowing time off for union duties by Monday. The issue has been deadlocked for two years.
Donald Thomas, head of finance and personnel in South Lanarkshire's education department, said the council wants a "realistic entitlement" to cover all unions and a range of duties.
David Liddell, honorary secretary of the EIS in South Lanarkshire, said a number of issues had strained relations between the union and the council, including "unilateral" cuts in travel expenses to parents' and in-service meetings and the loss of music instructors' jobs.