The 141 bus serves places like Hucknall, Linby, Papplewick and Newstead before going on to Nottingham and places like the City Hospital.
It has been described as a ‘lifeline’ for residents and serves some of the areas with the lowest car ownership in Nottinghamshire’.
But the company says the service is not carrying enough passengers to justify continuing to run it.
Coun Jason Zadrozny (Ash Ind), Ashfield District Council leader and Independent Alliance leader at County Hall, has started a petition to save the service, which has now gained more than 2,500 signatures.
Coun Zadrozny has also tabled an urgent question about the service cancellation for the full council meeting at Nottinghamshire County Council on Thursday, July 7.
Coun John Wilmott (Ash Ind), who represents Hucknall North at County Hall, said: “The 141 is a lifeline for so many residents in Linby and parts of Hucknall – especially for those using City and Kings Mill Hospitals and those working in Nottingham.
"Trentbarton have run the most unreliable service in the county of late and have used the resulting lower passenger numbers as an excuse to axe this critical service.
"Nottinghamshire County Council has cut funding, despite promising to increase it.
"I hope the huge amount of residents who have signed our petition will force a re-think.”
Fellow Hucknall councillor Lee Waters (Ash Ind), who represents Hucknall South at County Hall, added: “I used to get the 141 every single day and I’m absolutely dismayed to hear this service could be stopping.
"Many of the people who have signed the petition about this are from Hucknall who are fighting to keep this bus service open.”
Jeff Counsell, Trentbarton managing director, said: “We are very sorry indeed that we must make these changes but in order to continue to deliver our other services we cannot afford to absorb the losses made by these routes, which simply do not carry sufficient customers.
“The routes affected had been struggling before Covid and have not seen the bounce back in numbers that other services have seen.
"The Government has been supporting the bus industry since the pandemic hit but this help ends this autumn.
“The silver lining in what was a very difficult decision is the extra drivers we can put on to our other services which will mean much fewer cancellations and a significantly improved reliability.
“The changes will enable us to run more services, more frequently, on the journeys that most people need, growing customer numbers and making them more sustainable.
“We are talking to the local authorities and other operators to see if they can support any of the affected routes.
"Some customers will also be able to access other Trentbarton services and those of other operators.
“We apologise to all our customers who will be affected.
"Running buses is what Trentbarton exists to do, so to cancel routes is always done with a heavy heart and when there is absolutely no other option.”