Two-week waits to see a family doctor could soon be commonplace, a leading medic has suggested.
Waiting lists are set to soar as GPs are stuck between a mismatch of rising demand and "disinvestment", the chair of the British Medical Association's general practitioners committee said.
Dr Chaand Nagpaul warned that general practice is "imploding".
There is now a "conveyor belt of care" as GPs try to see as many patients as possible, he said.
He also warned that thousands of patients could be left without access to a GP because of changes to the way practices are funded.
Speaking to the BMA's annual representative meeting in Harrogate, Dr Nagpaul said that in the last five years the number of patients seen by family doctors has increased by 40 million each year.
But despite the increase in workload, there has been a reduction in the number of family doctors and their share of the NHS budget is "dwindling", he said.
"Funding cuts now threaten the viability if many GP surgeries nationally," he said.
"We've similarity seen a relative reduction in the GP workforce, with the number of GPs as a proportion of doctors in England reducing from 34% to 26% in the last two decades.
"The simple fact is that demand has far outstripped our impoverished capacity, denying patients the care and access they deserve.
"We're forced into providing a conveyor belt of care at breakneck speed. This is unmanageable, exhausting and unsustainable and puts safety and quality at risk.
"I urge politicians to open their eyes and wake up to the fact that general practice is not just in a crisis, it's imploding."
On rising waiting times, he added: "What we are witnessing is a total mismatch between the rapidly rising demands on GP appointments and a shrinking capacity to provide that care.
"Waiting times are inevitably getting longer because the increased demand has not been matched with increased capacity.
"GPs will rightly prioritise urgent problems, what is being squeezed are patients with routine problems.
"This is paining GPs, we want to provide prompt and good care but it's just proving impossible.
"It's common that patients wait over a week, some two weeks. The Royal College of GPs have done a survey which shows that waits will increase to two weeks in a large number of practices in the coming year."
Later delegates at the conference will debate on a "destabilising" change to the way NHS funding is allocated.
Recently the Royal College of General Practitioners warned that surgeries have been struggling to pay their bills since the changes came into force earlier this year.
In April, the Government began phasing out the Minimum Practice Income Guarantee over a seven-year period.
The funding scheme means many smaller GP surgeries are guaranteed a minimum level of funding that is not dependent on the number of patients on their practice list.
The college said that 98 practices are at threat of imminent closure because of the changes.
Dr Nagpaul warned that this could leave thousands of patients without a family doctor. And many more surgeries could face the same fate, he added.
"There is a real worry that in the coming two years we are going to see significant numbers of practices that are going to be in unviable financially.
"In certain areas, especially remote areas - there are two in Cumbria where if they close, patients will have to cross a lake to get to the next practice - so there is real risk patients will be left without a practice in some rural areas."
The BMA will later debate a motion calling on the Government to reverse the decision to phase out the funding scheme - which creates a third of funding for some practices.
A Department of Health spokeswoman said: "It is scaremongering to say that GP services are 'imploding'.
"The number of GPs has gone up by 1,000 since 2010 and we've taken tough decisions to protect the NHS budget so we can strengthen family doctoring, reform out-of-hospital care and improve GP access for 7.5 million people.
"GPs agreed to be at the heart of our radical plans for more personalised community care in return for cutting their targets by more than a third to free up more time with patients."