More than 50,000 Victorian state school teachers and principals are preparing to strike unless the Andrews government fixes their "crushing" workload.

Lengthy pay and workload negotiations between the Australian Education Union and the state government escalated on Friday, with the union's branch council voting to take steps towards industrial action.

Teachers rally at Hisense Arena in June 2012. Credit:Jason South

The sticking point is not so much about pay, but relief from excessive workloads.

The move towards widespread industrial action could result in schools closing as teachers take part in planned workplace stoppages.