Campaigners are to call on Prime Minister David Cameron to rethink the pace of GCSE reforms.
A letter signed by nearly 100 groups is expected to be handed in to 10 Downing Street asking for a meeting with Mr Cameron and Deputy Prime Minister Nick Clegg to discuss the proposals.
Education Secretary Michael Gove announced plans last year to scrap GCSEs and replace them with new English Baccalaureate Certificates (EBCs), starting in 2015.
But campaigners, including individuals from the world of education, the arts, design and industry say they are concerned about the current review of secondary school exams, and the consultation on introducing EBCs.
The letter says: "Whilst not being opposed to the reform of the system of examinations, nor to the drive to raise standards, we are concerned that the current consultation on the introduction of English Baccalaureate Certificates is too limited and that decisions are being made too quickly.
"We need an examination system which ensures pupils receive a rigorous, broad and balanced curriculum. We do not believe the current proposals for EBCs will do that.
"By failing to give parity to high quality creative and vocational subjects, as well as sport, these reforms will jeopardise our children's education and undermine the economic and cultural health of our nation."
It calls for an extended consultation period, with views sought from parents, students, governors, businesses, teachers and headteachers.
"A small group of the signatories to this letter would welcome the opportunity to meet with you to further explain our concerns and discuss ways in which the Government could initiate a national conversation about examination reform," the letter says.
It is signed by a range of individuals and organisations including the National Union of Teachers (NUT), the National Association of Head Teachers (NAHT), Nicholas Hytner, artistic director of the National Theatre, Sandy Nairne, director of the National Portrait Gallery and Rosemary Johnson, executive director of the Royal Philharmonic Society.