Image source, Getty ImagesThe Liberal Democrats have called for everyone over 70 or with a long-term health condition in England to get access to a named GP.
The party said a "return to the family doctor" would help avoid hospital appointments and save the NHS money.
Patients in England over 70 have had a named GP since 2013, with this extended to all patients in 2015.
But Lib Dem leader Sir Ed Davey told the BBC this was "a tick-box exercise" that had not been implemented.
The party said their policy would ensure over-70s and those with long-term health conditions – an estimated 18.7 million people – would be offered appointments with their named GP as a first option wherever possible.
It said these groups had been found to benefit the most from having access to the same GP.
The Lib Dems have already pledged to give everyone a legal right to see a GP within a week or 24 hours if in urgent need.
Sir Ed said: "We want to see the return of the family doctor, so patients with long-term care needs see the same GP and don't have to waste time repeating their details from scratch at every appointment."
He told the BBC's Sunday with Laura Kuenssberg programme 8,000 more GPs would be needed to deliver the scheme, which would take "at least four years" and an extra £1bn each year to implement.
However, he argued it would save the NHS money in the long term as people would not need to go into hospital so often.
Under the current system a patient's named GP has overall responsibility for the care provided by the surgery. However, people are still able to see any doctor who is available.
Labour has also promised to cut red tape so patients can see the same GP each appointment if they choose, with shadow health secretary Wes Streeting saying GP practices would be provided with incentives to offer patients continuity of care.
The Department of Health and Social Care has been approached for comment.