A union for education leaders, such as head teachers, says it will write to Gavin Williamson over the “fiasco”.
Mr Williamson apologised to students after reversing how A-levels and GCSEs are graded, following heavy criticism.
Meanwhile, pupils will get GCSE results on Thursday as planned, the Joint Council for Qualifications (JCQ) said.
The confirmation comes following confusion over how results day would run after the government U-turn.
Julie McCulloch, director of policy at the Association of School and College Leaders (ASCL), said the JCQ’s confirmation would be a “great relief” to all concerned.