Proposed GP contract changes may force senior GPs to walk away from their commissioning commitments, it is claimed.
Dr Peter Swinyard, chair of the Family Doctor Association (FDA), said the proposed government changes to the 2012/13 GP contract are a "toxic mix" of increasing workload, diminishing resources and rising expectations.
He said the changes risk "poisoning" relationships between the government and practices "at a time when the government really rather needs us to be keen and enthusiastic in doing wonderful things in commissioning".
"If the government seriously thinks GPs are stupid enough to want to go into clinical commissioning groups (CCGs) when they are under such pressure in their practices, then they are wrong," said Dr Swinyard.
"I can see a lot of good GPs and senior GPs who have been helping run their CCGs who are going to have to back away from commissioning to cope with the increased workload they will have in their practices under the new contract."
Dr Michael Dixon, chair of the NHS Alliance and interim president of NHS Clinical Commissioners said while most GPs are happy with the concept that the quality and outcomes framework (QOF) is to be "ratcheted up", he expressed concern the GP contract is "going down a biomedical route rather than a patient-led one".
"Some of the new clinical indicators proposed will take up an awful lot of time and effort for an agenda that is not patient-led and will not make an awful lot of difference," said Dr Dixon.
"I am worried that GPs will become more focused on getting the figures in place rather than getting involved in improving the health of their population."
A spokesperson for the NHS Commissioning Board said: "The Department of Health is currently consulting on these proposals - and it will be for the Department to make decisions on the way forward in the light of consultation responses."
A Department of Health spokesperson said: "Improving patient care and saving more lives is what GPs have trained to do. As members of CCGs, they will be able to make sure local services are in place to support better care for their patients.
"Putting patients first and improving their health must be our priority, however, where possible, our proposals have been specifically designed to help practices manage workload at the same time as improving patient care."