Doug McAvoy told delegates at his union's conference in Scarborough that members of the two other teaching associations must feel as strongly as they did about the tests.
In a survey, NUT members had overwhelmingly rejected the tests, he said. The National Association of Schoolmasters Union of Women Teachers and the Association of Teachers and Lecturers have called off their ballots without formal consultation.
'I cannot believe that our colleagues in the NASUWT and the ATL think differently. Yet, sadly, their organisations are snuggling up to the Government and Baroness Blatch rather than standing alongside us,' he said.
In a speech that significantly failed to mention the calls for strikes which were passed this week against the wishes of the executive, Mr McAvoy concentrated on issues which could unite his members.
He condemned the Government's attempts to impose testing and assessment, spending cuts and the introduction of specialist schools, which he said would only benefit a minority of children.
The union would also campaign for amendments to the Deregulation Bill to improve school minibus safety.
The union rejected two calls for more radical action after a week in which the left appeared to have the upper hand.
Delegates rejected motions which would have led to strikes over redundancies and which would have changed union rules so that a two-thirds majority was no longer needed to call a strike.
But they supported moves to amalgamate with other unions to form a single teaching union by 1996.Reuse content