School leaders in Moray have described their workloads as "unmanageable" since the council became the first in Scotland to scrap principal teachers, saying that important tasks were being neglected in schools.
A survey of staff in Moray found that literacy and numeracy groups had been abandoned, Curriculum for Excellence was progressing more slowly and staff were feeling "very vulnerable" about school inspections.
Despite this, other councils across Scotland are poised to follow Moray's example in a bid to cut costs, with East Lothian already planning to do away with PTs.
Since the start of the school year, 49 PTs in Moray have been reclassed as classroom teachers with no management role. The time they were allocated for curriculum development has also been removed. Those whose posts have been axed will remain on their current salary for three years, after which they will return to classroom teacher pay. The move is expected to save about pound;190,000.
"Staff morale is at an all-time low and workload pressures are becoming more and more evident," said Susan Slater, the secretary of the Moray branch of the EIS teaching union, which conducted the research.
Survey responses showed that workloads for school leaders and depute headteachers had become unmanageable, Ms Slater said: "They are no longer able to delegate tasks within their schools and the reality is that not everything can be done and the pace of Curriculum for Excellence has slowed."
Ms Slater added that many schools in Moray were small and had no depute head, so the work of PTs was "invaluable".
In addition, she said, a number of PTs had been members of groups charged with improving literacy and numeracy across several schools, but these had been disbanded.
One school leader told the survey: "We are no longer able to lead our schools - we have become managers that have time to deal only with day-to- day issues; we are basically firefighting."
Another said: "With no one now in school to support me as headteacher I am doing everything . There will be things not achieved this year in terms of moving the school on as I simply do not have the capacity to teach three days and run my school as before."
Another school's submission said: "Workload has increased upwards to the headteacher and curriculum development has slowed down. Staff are feeling the pressure of not being able to move forward at the pace that is required to make significant changes."
Larry Flanagan, general secretary of the EIS, said that the union was "opposed to the removal of hard-won posts such as primary PTs - an action which will only exacerbate workload pressures in schools, in the same manner that faculty arrangements in secondary have done".
Last Friday, the union's council passed a motion opposing the removal of promoted posts to save money and agreed to collate national figures on how many had been cut.
Greg Dempster, general secretary of primary school leaders' body AHDS, agreed that the loss of PTs was "extremely worrying". "The Moray experience has been a huge erosion of management capacity within schools while the workload expectations continue to grow," he said.
"There will no doubt be the argument that `distributed leadership' practices mean that many tasks can be passed to teaching staff. This is simply unrealistic for two reasons: the first is that class teachers already have a heavy workload; the second is that many of the tasks which need to be done are management roles and teachers - and their unions - will strongly resist the passing on of these duties.
"This means that the removal of PTs heaps work on to already stretched headteachers."
Laurence Findlay, Moray's head of schools and curriculum development, said that the council would look for ways to address the concerns of staff and would evaluate the impact of scrapping PTs.
It was "far too early" to prejudge, Mr Findlay said, although he did concede that a "significant" number of schools now had no management staff other than school leaders.
Mr Findlay added that although some inter-school groups with a variety of remits might no longer be running, authority-wide literacy and numeracy groups still existed.
Meanwhile, an East Lothian Council spokeswoman said that the authority was proposing to save pound;150,000 by scrapping all 47 principal teacher posts, with consultation running until tomorrow. This would enable the council to keep classroom teacher numbers at current levels in line with Scottish government requirements, she said.