HEADS will next week deliver an ultimatum to Education Secretary Charles Clarke - double your money or say goodbye to the workload agreement.
The National Association of Head Teachers has issued its threat, despite pound;800 million extra for schools announced last week.
The union estimated that before the extra money was announced, ministers needed to provide an extra pound;1.5 billion by 20056 to meet their promise of pound;3bn over three years to implement the agreement.
That means that a minimum additional pound;700m is needed over the next two years. Unless the money is forthcoming, the union will withdraw from the agreement, which involves teachers being relieved of administrative tasks and classroom assistants taking classes.
David Hart, general secretary of the National Association of Head Teachers, said: "The Government has a potential electoral disaster waiting to happen.
Charles Clarke's statement has bought the Government some time.
"But there is anger among heads that there is nothing for this year, and extreme concern that the Government will not deliver what is necessary for the next two years."
In his statement last Thursday, Mr Clarke promised that next year every school will be guaranteed a real-terms increase in funding per pupil.
He also announced that schools will receive pound;400m extra in each of the next two years as a result of maintaining the standards fund at its current level.
Every council will be expected to pass on increases in school spending in full and retain less of schools' budgets centrally.
The National Union of Teachers and Local Government Association said that Mr Clarke's continuing pressure on local education authorities to put more money into school budgets would damage support for excluded pupils and those with special educational needs.
"The most vulnerable will be penalised because the Government has not done its sums properly," said John Bangs, the NUT's head of education.
The NUT will also oppose the suggested two-and-a-half year pay deal for teachers because it believes that this year's deal will be affected by funding problems.
Martin Ward, deputy, general secretary of the Secondary Heads Association, said that pulling out of the workload agreement would be a futile gesture because schools would still have to implement changes in teachers'
contracts. But he agreed that it would mean schools cutting back other spending unless more money is found.
The row over this year's funding continues to rumble on in the local press.
Parents at Hotspur primary school, Newcastle, have written to Mr Clarke accusing him of putting their children's education at risk after the school was forced to lose one full-time and one part-time teacher.
And Peter Abraham, Bristol's education chair, has demanded an apology from Mr Clarke. He said it was the Government, not councils such as Bristol, that had been holding on to funds.