Conservative plans to prevent those without top exam or degree results from becoming teachers could dramatically affect the supply of trainees in shortage subjects such as science and maths - and applications to BEd courses - universities have warned.
Michael Gove, the shadow schools secretary, pledged last week to make sure every new primary trainee has a B-grade in GCSE maths and English and a 2:2 degree or above. But teacher trainers warned that this could stop candidates from disadvantaged backgrounds entering the profession.
They are concerned that the Tories' plans could stop career changers or teaching assistants gaining places on courses - even if they have the potential to become excellent educators.
Entry requirements for undergraduate teacher training courses have been rising steadily at most universities, and trainers say there is no need for arbitrary changes to entry requirements.
Dr Sue Beverton, divisional director of initial teacher training at Durham University, said: "Increasing the skills of those entering teaching isn't a bad thing, but not if it's at the expense of losing people who have really important qualities and skills.
"I don't feel it's quite as simple as just saying, 'We're going to raise the bar.' Instead the emphasis should be put on the selection process. People don't stop learning at GCSE; they might go on to change their approach to exams after.
"It's important that teachers come from a mixture of backgrounds."
University of Wolverhampton applicants take extra tests in English, maths and science to check their knowledge, and if it is not up to scratch they are given work to do before the course starts.
Jeff Serf, head of the university's primary teacher training, said: "If, by raising the bar, these changes block people from the profession who would have been outstanding teachers and role models, that would be a bad thing.
"I'm also concerned about the affect this might have on priority subjects, especially maths. It's all very well stipulating a 2:2 or above, but what if this cuts the number with shortage subject degrees coming forward to train as teachers?"
John Bangs, head of education at the NUT, has advised Mr Gove to "think very carefully" about his plans.
"It might victimise people ... who go through the system from different backgrounds," he said. "The Conservatives need to recognise that teachers also learn on the job."
Mr Gove also wants to allow trainees only one resit of the basic literacy and numeracy tests they have to pass to qualify as teachers. He believes 13 per cent of applicants - about 5,000 - currently sit the on-screen numeracy test three or more times.