The number of family doctors leaving general practice in England slightly outstripped the number joining the profession in the first three months of the year, figures show.
The total headcount of GPs working in general practice was 42,250 as of March 31, according to new experimental statistics from NHS Digital.
From January to March a total of 830 GPs left general practice. But just 789 joined the profession, the data show.
Leading doctors said that the news comes at a time when 5,000 more GPs have been promised.
Dr Krishna Kasaraneni, lead for GP education training and workforce at the British Medical Association (BMA), said: "These figures demonstrate the failure of politicians to uphold their pledges to deliver the GPs necessary to provide the number of appointments and sustainable service that patients deserve.
"The overall number of GPs working in England has dropped since 2015, which leaves the NHS a considerable distance short of the current targets for the GP workforce.
"There is little prospect of the promised 5,000 additional GPs materialising anytime soon.
"This continued workforce crisis has left many GP practices unable to properly staff their surgeries at a time when local services are struggling to cope with rising patient demand and flat-lining budgets.
"The next government must ensure that we have a properly staffed service that can meet the needs of patients."
Professor Helen Stokes-Lampard, chairwoman of the Royal College of GPs, said: "Workload in general practice is soaring - 16% over the last seven years, according to the latest research - yet our workforce has not risen in step, and is now actually reducing.
"This isn't acceptable."