The government is threatening to take money away from GPs and give it to local health authorities unless they agree to open their practices an extra three hours a week from April.
Prime Minister Gordon Brown has pledged to make surgery times more family friendly but doctors say there is no evidence that longer opening hours will improve patient's health.
The British Medical Association said its General Practice Committee had concluded on Thursday that working the extra hours was the least bad option, as it was unsure how local health authorities would spend the reallocated money.
The BMA will poll GPs this month in a consultation on the proposals. But it denied it had backed down in the dispute with the government.
"GPs have been put in an impossible position and will have to choose between two unacceptable alternatives," said Laurence Buckman, Chairman of the BMA's GPs committee.
"We have been asked which of these two is less bad and we have responded to GP demand that we do that.
"We are not recommending any course of action and GPs are free to come to their own decision on how to vote."
Most GP practices opted out of providing weekend and overnight cover under a contract agreed with the government in 2004.
Health Secretary Alan Johnson wrote to all GPs earlier this week urging them to accept the proposal to extend surgery times.
But a poll of 350 family doctors by GP magazine this week found that 65 percent would reject Johnson's plea.
