The former head of Ofsted, Amanda Spielman, has criticised the education secretary and accused her of giving "a great deal of time and attention" to the teaching unions.
Speaking to the Daily Telegraph, Ms Spielman claims "effective reforms are being reversed" - referring to potential changes to academy schools' powers.
The Children's Wellbeing and Schools Bill is set to change the rules around how academies pay their staff and the material they can teach, which critics say threatens their autonomy.
But the Department for Education (DfE) says its "landmark" reforms deliver on its mission to ensure all schools can attract and retain the best teachers.