Ministers are bracing themselves for industrial action over primary school tests and are digging their heels in for a battle with the largest teaching union.
Ministers privately admit they expect rank and file teachers will back the boycott of tests for seven and 11-year-olds.
But the Government is refusing to bow to the National Union of Teachers' demands for a review of the testing regime and insists staff have little enthusiasm for a long period of industrial action.
Charles Clarke, the Education Secretary, has not ruled out court action to prevent industrial action which ministers believe may be unlawful.
Surveys conducted by the NUT suggest that more than 80 per cent of members would support a boycott of key stage 1 tests and 70 per cent back action against tests for 11-year-olds.
The Government hopes support for the boycott will weaken once the practicalities of implementing it in individual schools become apparent.
Mr Clarke has written to Doug McAvoy, NUT general secretary, accusing him of behaving irresponsibly by balloting members over a boycott.
He warned that the union should not assume that the Government would not challenge the legality of industrial action.
Mr Clarke said the union's call for a review ignored the examination of primary education which resulted in the Government's Excellence and Enjoyment document.
The primary strategy includes a KS1 tests pilot scheme to give greater weight to teacher assessment and gives schools greater control of targeting setting at KS2.
"I am amazed that you are not prepared to give these important policy developments a chance to be implemented and evaluated before you embark on what could potentially be a damaging course of action for thousands of pupils," Mr Clarke said.
But John Bangs, NUT head of education, accused ministers of rewriting history.
"This is an extraordinary statement. Excellence and Enjoyment was a review of the literacy and numeracy strategies, not of the testing regime. It was certainly not the kind of public review carried out in Wales and Scotland.
"If there is any irresponsibility, it lies with the Government."
Relations between the Government and the NUT have been on a downward spiral since the union's decision in January not to sign the workload agreement.
The decision to hold a ballot follows a motion attacking the tests at the NUT's annual conference which was boycotted by ministers.
Ballot papers were sent out last week and the result will be announced on December 15.
A boycott will begin next term if it wins the support of half the electorate and at least two-thirds of the teachers who vote.
More than 100,000 NUT primary teachers will be expected to refuse to undertake tasks such as coaching pupils for tests, setting targets or taking part in test-related training. The union has promised that no child's education will be disrupted.