Conservative leader David Cameron has revealed he is ready to renegotiate GPs' contracts to give them more responsibility for increasing out-of-hours care.
The Tories admit they cannot change the system back to the previous personal obligation on family doctors to provide evening and weekend services.
But they believe that giving them a commissioning role could improve the situation.
A new Conservative Party document states: "Many PCTs have, because of their own deficits, been unable financially to commission enhanced access for GPs, including evening and weekend surgeries.
"GPs, as budget-holders and Primary Care commissioners, will be in a position to respond to the interests and wishes of their patients."
But Dr Laurence Buckman, chairman of the British Medical Association (BMA) GPs committee, said the Tories have "failed to understand" the issues around why the contracts were brought in.
"All sides recognised that the UK had too few family doctors," he said.
"Recruitment was at an all-time low, and doctors were thinking of taking early retirement because of the unsustainable workload.
"It was not safe to ask exhausted GPs to work nights and weekends as well as in the daytime. The new GP contract has delivered better quality of care with pay linked to the standards of services provided.
"The Conservative plan to turn the clock back will not help patients overall."