Academies will come under renewed attack at the Trades Union Congress annual conference in Brighton next week.
Delegates are expected to back a motion that has been proposed by the National Union of Teachers and backed by the Association of Teachers and Lecturers calling for a national campaign of demonstrations against the privately-sponsored schools.
It comes as 10 academies opened their doors to pupils this term. They include Salford City academy, sponsored by the United Learning Trust, which now has four of the semi-independent secondary schools, with three more confirmed and a further four schools in the pipeline.
The new additions will make Middlesbrough England's academy capital, as the Macmillan city technology college converts to become its third academy.
The sponsor of another Middlesbrough academy, Sir Peter Vardy, the Christian fundamentalist car dealer, also adds to his portfolio this month with the opening of Trinity academy in Doncaster.
The motion to the TUC states that academies fail to provide adequate educational support to vulnerable communities and lead to pupil election and undermine local democracy, equality of access to high-quality education and the ability of schools to work together.
It says academies represent a threat to staff pay and conditions.
In addition, the motion to the TUC says, academy teachers should be in communication with all other state-sector teachers.
This week, however, Ruth Kelly, the Education Secretary, signalled that it will be full steam ahead with the controversial programme.
"Academies are a key part of our reform agenda," Kelly insisted. "There will be no let up in the pace at which we roll out this programme."