Passengers fear that bus firm Stagecoach’s 35 service – which connects Huntingdon to the March area – will be axed in the new year.
There are also concerns over the future of the 30 service to Ramsey.
Two regular passengers contacted The Hunts Post to say they had been told by drivers that the 35 bus was to be cut.
One said that a driver had told her that he and three others had lost their jobs.
The 35 bus proves a vital link between Huntingdon and the fens and passengers include workers, schoolchildren and people visiting Hinchingbrooke Hospital.
A passenger from Warboys, who did not want to be named, said her job in Huntingdon could be in jeopardy if the bus stopped running.
Andy Campbell, managing director of Stagecoach East, said: "We are looking at a number of services that have been underperforming - but discussions with the county council are ongoing and it is too early to say what the future holds."
Beverley Wickenden, from Chatteris, said her 17-year-old son, a student who also had a job in Huntingdon, had been on his way home when one of the drivers told him that the service would be cancelled with effect from the new year.
She said she had not been able to find any information about the move and had been in touch with Stagecoach and her MP
"My son uses this bus on weekdays to get to and from school. He also works in Huntingdon on Saturdays and I personally use the bus to get to the opticians, dentist and for clothes, shoes, books and household items, as well as accessing the train stations in March and Huntingdon, since I do not drive, nor have access to a car," Miss Wickenden said.
"My eldest son, who is 20, is already struggling to find work and this potential cancellation will adversely affect him and many others."
Miss Wickenden said her younger son, who is studying A levels at Hinchingbrooke School because his local secondary did not offer the subjects he wanted, already had to leave school early after Stagecoach last year cancelled the bus he used to get home.
The passenger who did not want to be named said she would not be able to get home from work without the bus.
"It would be a problem, to be honest, and I would probably have to look at a different job," she said.
A spokesman for Cambridgeshire County Council said: "We're aware that Stagecoach is looking at some of their local bus routes. Discussions with the company are at an early stage but further information will be provided once details are available."