Research carried out by the National Union of Teachers found that 56 per cent of teachers questioned would support merging the existing three exam boards, despite fears that it would reduce choice. Fewer than a third wanted to retain the system with the rest undecided.
A third of the 236 teachers and sixth-form lecturers who responded to the survey were unhappy with the service provided by the boards, although 59 per cent were satisfied.
John Bangs, head of education at the NUT, said: "The three exam boards are in the last-chance saloon. This survey is a real wake-up call."
The findings come days after former chief inspector Mike Tomlinson published his second report into what went wrong in this summer's A-levels. He recommended significant changes to the system but not a reduction in the boards.
The survey suggests that dissatisfaction has increased since the advent of AS and A2 exams. Two in five teachers say the service has deteriorated. Reducing admin, common procedures and improving communication were the main reasons given for a single board.
Apart from concerns over choice, - shared by more than half of respondents - the main argument in favour of maintaining the status quo was a belief that competition between the boards leads to lower fees and improved service.
Despite frustration with the service, not all teachers blamed the boards. While some said they were "hopeless" at dealing with queries over the phone, others praised their willingness to help.
One teacher told researchers: "The real problem is the ridiculous proliferation of exams - the fault lies with the Government."
A spokesperson for the Qualifications and Curriculum Authority said there were no plans to reduce the number of boards: "The independent panel of international experts concluded that the current system provides greater choice for schools and colleges. Having more than one awarding body limits the risk of a single systems failure affecting all candidates."