Scotland's biggest council union is planning strikes that could close schools across the country next month.
Unison members backed action in 24 of the 32 council areas after rejecting an average pay increase of 5.5%.
The strikes will involve catering, cleaning, pupil support, administration and janitorial staff in schools and early years centres.
Unison Scotland convenor Lilian Macer said workers had been put in an "untenable" position by Cosla.
The union later confirmed the action will take place in every local authority with the exception of Midlothian, Falkirk, Scottish Borders, Argyll and Bute, North Lanarkshire, East Lothian, West Lothian and East Ayrshire.
No dates have been confirmed yet, but Unison's local government committee will meet this week to prepare for the strikes.
'Strong' pay offer
Cosla said the "strong" pay offer represented a 7% rise on average, with the lowest-paid council workers receiving a 9%-plus increase.
But Ms Macer said Unison had received the "strongest ever" strike mandate from local government workers.
The eight local authorities where no action will be taken all overwhelmingly backed the strikes, but fell short of the required 50% turnout.
She accused Cosla of "delaying tactics" over pay negotiations, but said the union would be open to further talks.
'No option'
"The last thing we want to do is disrupt children's education," she told the BBC. "We have been placed with no option. The Scottish Government's public sector pay policy makes no reference to inflation, makes no reference to the cost-of-living increase that members are facing. And, for years, members have been undervalued and underpaid."
Councillor Katie Hagmann, Cosla resources spokeswoman, said a special leaders meeting had been called to find a "swift" resolution to strike action.
The two other largest council unions also have mandates for action in several parts of the country.
GMB Scotland last week confirmed its members in 10 Scottish councils - including Aberdeen - would go on strike on September 13 and 14. Unite members in 10 local authorities also voted to strike over pay after the summer break, but it has yet to announce dates. None of the latter areas are in the North-east.