The Universities and Colleges Admissions Service (Ucas) will unveil proposals over the next few days to reform the A-level points tariff that is used to assess whether students are fit to embark on an undergraduate course.
Instead of ranking the top A grade as worth five times the value of a bare pass at grade E, it will suggest that an A should be regarded as no better than two or three Es.
The plan is being welcomed by headteachers' leaders who think the present system gives too little credit to the hard work and intelligence of lower achievers. But it is causing alarm among traditionalists who see any narrowing of the gap between top and bottom grades as evidence of falling standards.
The Ucas proposal is designed to provide a single scoring system for universities to measure three different types of qualification: A-level, the new intermediate AS level being offered soon for students at the end of their first year in the sixth form, and equivalent vocational qualifications.
It will also give points for candidates passing tests in the "key skills" of communications, numeracy and information technology.
Under the present system, candidates score 10 points for a grade A, eight points for a B, six for a C, four for a D and two for an E, the lowest ranking pass. Top universities set A or B grades in particular subjects as the entry requirement for their most popular courses, but others set a points target that candidates can reach by mixing and matching lower grade passes.
Under the Ucas recommendation, candidates would score 120 points for an A, 100 for a B, 80 for a C, 60 for a D and 40 for an E. All the numbers have been set high to allow courses to be broken down into modules and points awarded for each. But the main purpose of the change is to narrow the points differential between an A and an E.
John Dunford, general secretary of the Secondary Heads Association, said the move would give proper recognition to a wider range of achievement. "The present system is far too narrow. It gives too little credit to a candidate who gets an E grade after passing the exam with as much as 45% when another candidate can get an A grade for passing with as little as 68%."
Graham Able, master of Dulwich College and chairman of the academic policy committee of the Headmasters' Conference, said: "Independent schools would be happy with 40 points for an E and 120 for an A. That ratio is about right. The present system undervalues an E. This will help to motivate everyone by giving a reasonable value to a bare pass and more for a top grade."
The Ucas consultation paper will suggest an alternative option making an A worth two Es, but Mr Able said this would be rejected for fear that weaker schools might be encouraged to push pupils to pass more subjects at a lower level to boost the school's standing in league tables.
There were signs last night that the government was anxious about the proposal. Sources close to David Blunkett, the education and employment secretary, said: "Ucas is an independent body and it has the power to make these suggestions.
"But we would intervene to veto any proposal that appeared to reduce the standing of A and B grades. We don't want the top universities breaking away and introducing their own exam system."
David Willetts, the shadow education secretary, said: "You cannot get parity of esteem out of the barrel of a gun. Esteem has to be earned in the minds of people in the universities.
"Those who use A-level as a test of students' ability and understanding will be very wary of a change that appears to undervalue good A grade candidates."
Sheila Lawlor, director of the rightwing think tank Politeia, said it was depressing to imagine that students might qualify for university with E grades.
"For too long, the British education system has been pitched at improving the performance of the lowest achievers, but the universities should have proper differentiation and a good candidate does not get lots of Es."
Tony Higgins, the chief executive of Ucas, would not comment on the proposals before publication. but he did say: "I can confirm we are working on a new points tariff. We hope it will more accurately reflect performance in exams than heretofore."
