GPs will vote on whether to start charging patients for appointments, which they say will take some of the burden off family doctors.
Missed appointments cost the NHS £160 million a year and many doctors feel it's unsustainable to continue offering free care.
Family doctor's have increasingly voiced concerns over strains put on GP services by the growing number of obese and elderly patients.
They will cast their vote at the British Medical Association Local Medical Committees (LMCs) Conference later this afternoon.
Ed Miliband has pledged that a future Labour government would give GP surgeries an extra £100m funding and make sure all patients can see a doctor within 48 hours.
Speaking in Manchester, Mr Miliband said it was a "scandal" that only 40% of NHS patients are seeing a GP within 48 hours, while one in four cannot get an appointment the same week they ask for one.
The Labour leader said the extra money would come from getting rid of the market-based NHS framework set up by the current government, along with cutting spending on consultants and senior managers.
Over seven million patients are expected to benefit after 1100 GP practices announced they were to extend their hours.Read the full story ›
The amount of work GPs have to do is so great is its "threatening" the future of family medicine, the BMA has warned.
Dr Chaand Nagpaul, chairman of the BMA's GP committee, said:
It is clear general practice is facing a workload disaster that is threatening its long-term future.
We are seeing morale dip to a level that I cannot remember in my 25 years as a GP.
Six out of 10 GPs are considering early retirement and more than a third are actively planning to end their career early.
This could lead to a serious workforce crisis in general practice where we do not have enough GPs to treat patients.
The root cause of this crisis is that GP practices are facing an unprecedented combination of rising patient demand, especially from an ageing population, and declining resources.
Over half of GPs are considering stepping down and retiring before their mid-60s because of their heavy workload, the doctor's union has warned.
The British Medical Association (BMA) quizzed 420 GPs, 54% of whom said they believed their current workload was "unsustainable".
And 55% said their morale was "low" or "very low".
The union said that general practice is facing a "workload disaster".
As many as two million people have to wait up to three weeks for an appointment with a GP, a survey has found.
Half a million face a wait of up to a month to see their family doctor, while only one in three patients is able to secure a same-day appointment.
The research, carried out by the Daily Mail and over-50s group Saga, found that 20% of people cannot get a consultation within seven days.
Last week the Royal College of General Practitioners (RCGP) claimed more than 34 million people will this year fail to get an appointment with their GP when they seek one.[
More than 34 million people will this year fail to get an appointment with their GP when they seek one, the Royal College of General Practitioners (RGCP) has claimed.
The college's prediction that one in ten prospective patients will fail to secure an appointment when they wish is based on analysis of the latest GP Patient Survey, which was published in December.
The RGCP said the number of people who would fail to get an GP appointment when they want one will continue to rise as Government cuts and the effects of an ageing population take hold.
GPs now see 340 million patients per year in total but the NHS budget for general practice has been cut by £9.1 billion in real terms since 2004, the college said.
GP Dr Katharina Frey, who runs a small practice in Cumbria, appeared on ITV's Daybreak this morning to discuss her concerns over plans to phase out the Minimum Practice Income Guarantee (MPIG).
"Our actual patient numbers are quite low, but we have quite high overheads, so we don't really have the economies of scale" she told the programme.
Dr Frey warned the "viability" of the practice might be threatened by funding cuts.
"We want to be able to provide excellent care, but if more and more funding is going to disappear, this will be getting increasingly difficult."
The Government has decided to phase out a funding arrangement called the Minimum Practice Income Guarantee (MPIG) over a seven-year period, beginning in April - a move that doctors' leaders have warned could force around 100 GP practices to close.
MPIG means many smaller GP practices are guaranteed a minimum level of funding that is not dependent on the number of patients on their practice list.
NHS England has published an anonymised list of 98 'outlier' practices that could lose more than £3 per patient per year.
Some practices on the list will lose more than £100 per patient per year while others stand to lose around £20 or £30 per patient.
Around 100 GP practices could be forced to close due to cuts in national funding, leaving patients in rural areas without a GP, doctors' leaders have warned.
Changes to how practices are paid mean some could no longer be viable, despite the fact some "provide vital services to thousands of rural patients", the British Medical Association (BMA) said.
It warned that large areas of rural England could be left with no GP practice for local residents.