A city centre GP surgery with 3,500 patients could close down, along with an NHS walk-in centre housed in the same building.
Thousands of people may have to register with other practices if the surgery on King Street, which has a shortage of doctors, shuts next year.
But Wakefield’s MP Mary Creagh has said she will fight “tooth and nail” to protect it.
Ms Creagh, who is campaigning to save both the GP service and the separate walk-in facility, said: “More than 1,100 people have signed my petition to Save King Street Health Centre showing the deep public concern that people in Wakefield have about these proposals.”
The building’s walk-in centre, where people have been able to see medics without an appointment since 2009, was already under threat and could close next September.
But now it has emerged that the GP practice could also shut, six months earlier in March.
In a letter to patients, the NHS Wakefield Clinical Commissioning Group (CCG) said: “The service was recently rated as ‘Good’ by the Care Quality Commission (CQC), however the surgery has problems covering GP shifts.”
The CCG, which controls the district’s NHS budget, said it was consulting on whether to try to extend the GP service beyond March or help patients to register at other practices.
Dr Adam Sheppard, assistant clinical chair of the CCG, said: “The engagement we are currently undertaking which will run until December 30 relates to proposed changes about the GP practice registered list and will not affect the walk-in service. The contract to run the surgery is time limited and is due to come to an end on March 31.
“We have been discussing with our partners, and Wakefield Council’s Overview and Scrutiny Committee, a number of options to either try to extend the current service, or support patients to register with one of the nine other surgeries within 1.3 miles of King Street Health Centre - all of which are accepting new patients.”
Ms Creagh says she fears if the surgery closes, it could mean the end for the walk-in centre. She said: “These plans will also harm the future of the walk-in service which shares the same building, the same facilities and even the same staff as the GP practice at King Street Health Centre.
“Closing the GP practice would be a huge mistake and I will fight tooth and nail to keep both these vital services open.”
Health bosses are considering the future of the walk-in service as part of a separate review of urgent and emergency care, including A&E services.
Dr Sheppard said: “We’re looking at how we make urgent care services, such as those provided at the walk-in centre, available to patients across the district through their own GP surgery – giving patients access in their local communities.
“We’ve got some more work to do on this, which is why we need to have more conversations with people. Originally we thought it could mean the re-provision of the walk-in centre in April 2016, but we have extended this until September 2017 while we carry out a wider review.”
Registered patients have been sent letters detailing how take part in the King Street GP consultation.