Hundreds of schools and nurseries across Scotland might have to shut at the start of the new term if industrial action over staff pay goes ahead.
Council employees who work in education settings and refuse centres voted for strike after rejecting a 2% pay offer.
Unions said the walk-outs could happen after pupils return from the summer break in August.
The Scottish government said it was urging all parties to find a resolution to avoided industrial action.
Cosla, the local authority body, said they were waiting for the Scottish government to respond to requests for extra funding for councils.
A strike ballot of about 25,000 council workers from the Unison, Unite and GMB unions was said to be the largest in more than a decade.
Unite confirmed that its local government membership in 26 councils, and members at Tayside Contracts, voted for industrial action.
The required 50% turnout threshold required by the Trade Union Act was exceeded in nine Unison local authority branches -Glasgow, North and South Lanarkshire, East Renfrewshire, Inverclyde, Stirling, Aberdeenshire, Clackmannanshire and Orkney.