More than 600 people have signed a petition against NHS funding changes that could see half-a-dozen Sheffield surgeries close in the next few years.
The petition was launched last week by patients from the Devonshire Green and Hanover Medical Centres, where doctors have warned they may eventually have to shut as a result of the changes.
The campaign against the phasing out of the Minimum Practice Income Guarantee is being backed by Sheffield Central MP Paul Blomfield.
Campaigners claim as many as 13,000 Sheffield patients could be left without a surgery as the funding is phased out over a seven-year period.
The first reductions started last summer and some surgeries say they could lose over £100,000 in funding over time.
But NHS England has said the changes are planned to make funding fairer.
A spokesperson for NHS England said: “As part of a national process, the minimum practice income guarantee will be phased out with the view to allocating funds for core services based on the number of patients practices serve and the health needs of those patients to make funding more equitable.
“With regard to the Devonshire Green and Hanover Medical Centre, there are no plans to close this practice.
“We remain committed to supporting the practice in exploring various options including identifying other funding streams the practice could be accessing.”