A decision on industrial action over teachers' pay that could lead to a series of national strikes will be reached next week.
The ballot of about 250,000 members of the National Union of Teachers closes on Monday, with the final decision to be announced on Thursday.
Members have been asked if they support discontinuous industrial action, which could include national strikes and other locally coordinated action. If they vote yes, it would free the union from having to seek a separate ballot each time it wanted to take action over the current pay dispute.
The union is unhappy at teachers' below-inflation deal. Salaries went up by 2.45 per cent last month, but retail price index inflation hit 5 per cent at the same time. In April, a one-day strike led to some 9,500 schools in England and Wales being forced to close or partially shut.
Christine Blower, the union's acting general secretary, said: "Refusing teachers a decent salary will have a direct impact on children and young people's education. Teachers and other public sector worker unions cannot and will not stand by and see their members' incomes and standards of living cut."
John Dunford, general secretary of the Association of School and College Leaders, has said that given the present financial climate, with people struggling to pay bills and losing their jobs, there would be "non-existent" public support for teachers' strike action.