A quarter of a million school staff are likely to strike before Easter over proposed pension changes.
Teaching assistants, dinner ladies, secretaries and caretakers were this week asked to vote for action over the Government's plans to make them work longer for a full pension.
Unions accused ministers of double standards over their refusal to protect pension arrangements for existing staff despite agreeing to do so for teachers.
Unison, the largest support staff union, said the changes would cost a full-time teaching assistant earning pound;15,000 almost pound;2,000 a year from their pension if they decided to retire at 60.
If members vote for action the unions are likely to hold "a few days of all-out strike action" across local government before schools break up for Easter. That would be followed by selective action, including schools.
The Government's proposals would prevent all 1.5 million members of the local government pension scheme, including staff in council education departments, retiring before age 65 on a full pension. Although their official retirement age is already 65, support staff can take advantage of a provision which allows people whose combined age and length of service equals 85 or more to retire earlier on a full pension.
Unions are pressing for the rule to be protected for existing staff. They point to an agreement reached in October which will preserve the retirement age of 60 for teachers and civil servants.
Dave Prentis, general secretary of Unison, said: "All we are asking for is equal treatment with members of other public-sector schemes, such as teachers, the NHS and civil service. These are not Whitehall fat cats - the majority are women working as dinner ladies, teaching assistants, home carers and nursery nurses - and most provide crucial services directly to the public."
Ballot papers were sent on Monday by Unison, which has 200,000 members in schools and another 40,000 in council education departments, and the TGWU which has 8,000 school support staff members. A third union, the GMB, will send out papers to its 25,000 members in schools within the next two weeks.
The National Union of Teachers is preparing to ballot the 5,000 advisers and other local authority staff who are members.
A spokesman for the Office of the Deputy Prime Minister said: "The Government is committed to decent and secure pensions for local government employees. These must be affordable, viable and fair to taxpayers, who guarantee their security."
DOUBLE STANDARDS? EFFECT OF CHANGES TO RETIREMENT FUNDS
A teacher starting work today on an average annual salary of pound;30,000 pa who retired after 30 years' service at 60 could expect to receive a pension of pound;11,250 and a lump sum of pound;33,750.
A full-time teaching assistant who started work at the same time, earned half the teacher's salary (an average pound;15,000 a year) and also retired at 60 after 30 years' service would receive a pension equal to half that of the teacher - pension pound;5,625, lump sum pound;16,875. After the planned changes they would receive pound;3,750 pension, and a lump sum of Pounds 15,000.