Workers at the Department for Education have voted to go on strike in a row over spending cuts and job losses.
Members of the Public and Commercial Services union backed walkouts by almost 2-1, and other forms of industrial action by nearly 9-1.
The union said it believed Education Secretary Michael Gove is using the department as an ideological test-bed for wider civil service cuts.
Around 1,000 jobs are under threat because of spending cuts, said the union.
PCS general secretary Mark Serwotka said: "These cuts are purely political and would not only mean misery for 1,000 of Mr Gove's own staff but also put at risk some vital public services, such as ensuring children are safe at school and supporting special educational needs."
The union said turnout in the ballot was 37.5%. Officials accused the department of using management consultants to draw up plans to axe more than a quarter of its workforce.
Mr Serwotka said hiring a management consultancy, at a senior level in the department, should "ring alarm bells". He added: "There are serious questions to answer about a conflict of interest, given it would be allowed to bid for future contracts after receiving such privileged access."
A Department for Education spokesman said: "We are disappointed that the PCS has voted in favour of strike action. We have held extensive discussions with the PCS and we are consulting with staff on the proposed changes. We have made it clear that we want to avoid compulsory redundancies wherever possible.
"We want this country to have the best education system and the best children's services. To achieve this we must create a department that delivers an excellent service to the public, while ensuring value for money for the taxpayer.
"It is entirely wrong of the PCS to suggest that the DfE review will in any way have an impact on the safety of children or the support available for those with special educational needs."