The government has stepped up the pressure on GPs to work in the evenings and at weekends.
GPs pay has risen since a new contract came in
Ministers have warned they will push through a tougher deal if GPs do not agree to an extra three hours a week.
Doctors are willing to open for longer, but disagree over how long it should be for and the penalties for not doing so.
Gordon Brown has made extending GP hours a priority, although a survey of 2m patients earlier this year showed 84% were happy with opening.
The government said if doctors reject the offer in a poll to be carried out in the new year, it is prepared to impose tougher terms.
It would take out a hundred million pounds of extra funding, and reallocating a further three hundred million from within the existing GP contract to local primary care trusts, to spend as they see fit.
It comes after GPs have seen their pay rocket by 30% to £110,000 a year in the first two years of their new contract which started in 2004.
The British Medical Association, the doctors' trade union, has said it is happy to do extended hours without any extra money, but only wants to offer two extra hours a week for every 6,000 patients.
The average GP has a list of 2,000 patients meaning doctors would only need to do an extra 40 minutes.
The government, however, wants to see three extra hours for every 6,000 patients.
Officials also said the profession has been offered £100m to do this - something the BMA has disputed.
And crucially the BMA does not want the system structured in such a way that they would lose as much funds if they did not provide the extra hours.
There is also believed to be disagreement over how the extra hours should be provided, with the government wanting it to be done in 90-minute blocks whereas doctors want to be free to decide how it is done.
Ministers can push the proposals through without the agreement of doctors as long as they consult for 13 weeks.
Dr Laurence Buckman, of the BMA's GP committee, said: "We believe the government's method of negotiation is nothing short of a disgrace.
"They have effectively put a gun to our head and said if we don't accept their proposal they will impose a more draconian contract.
"The vast majority of our patients, and in particular those with chronic diseases or mothers with young children, prefer to come to surgeries during the day.
"They will be the ones who lose out if GPs are forced to work differently."
Health Minister Ben Bradshaw said the proposals would provide greater convenience for patients and were a good deal for GPs.
"It is disappointing that the BMA have not been able to agree to this, but we very much hope GPs themselves will back a proposal.
"If they do not, we will need to have alternative arrangements in place for next April."