Commuters face longer journeys if a peak-time direct service to Birmingham is cut, a rail users group claimed.
The 07:47 train from Wrexham to Birmingham has been omitted from a draft timetable for May published online, according to the Shrewsbury to Chester Rail Users Association (SCRUA).
If the service is axed commuters face waits of half an hour for a connection at Shrewsbury, the group said.
Arriva Trains Wales said "nothing has been finalised" on their May timetable.
Sarah Denney, who uses the service to commute from Ruabon, near Wrexham, to Telford, Shropshire, said she would have to catch an earlier train and wait for a connection at Shrewsbury.
"It would add to my commute, extend the working day and give me less time with my family," she said.
The RMT rail union said it "stands shoulder to shoulder" with the SCRUA in their fight to save services.
General Secretary Mick Cash said: "The train company needs to listen to the rail users and the staff and pull back from these ill-conceived plans before lasting damage is done to highly-valued and important services."
A statement from Arriva Train Wales said: "The development of the May 2015 timetable is still on-going and nothing has been finalised".
SCRUA said the draft timetable was published on the OpenTrainTimes website, which uses data "provided by Network Rail under licence".
A Network Rail spokesman said: "The train companies put forward the services they wish to timetable so it is a matter for them as to whether they have proposed to add or remove services."