One in six GPs are thinking about quitting the profession, according to a survey by the British Medical Association (BMA).
The study of more than 11,000 doctors revealed the extent of low morale among GPs, with more than half (53%) saying it had got worse in the past five years.
The BMA claims this is because of policies which place greater emphasis on cost-cutting and quantity of care rather than quality worries about the privatisation of primary care and a long-running "doctor-bashing" campaign.
Nearly two-thirds (63%) believe changes to the NHS over the past 10 years have made it harder to practise good medicine and only half (52%) would actually recommend a career as a GP to an undergraduate.
Laurence Buckman, chairman of the BMA's General Practitioners Committee, said: "We have serious concerns that the traditional core values of General Practice, in particular continuity of care, risk being lost as the government encourages increased private sector involvement."
The survey also deals a blow to government plans to extend GP opening hours. About half (53%) of GP partners would consider extending opening hours if the resources were available, but 73% do not believe it is a good way to spend NHS money.
"With regard to extending hours further beyond the current 8am-6.30pm, GPs remain to be convinced," said Buckman.
"Without specific, additional funding for extended hours, current services will become harder to sustain. It will mean surgeries will have to close during the day so they can be open in the evening."