Politicians are to fight plans to scrap trains between two of the biggest population centres in the West Midlands.
The West Midlands Passenger Transport Authority has told the Government's Strategic Rail Authority it cannot accept the proposed removal of the Walsall to Wolverhampton route.
The SRA had earmarked the line as one of the least used in the region and believes resources could be better employed to ease overcrowding on trains to and from Birmingham.
In March, just 2,000 people used the service, compared with 4,000 during the same period in 2004.
This compares with 546,000 passengers on the Birmingham Cross City Line last month. Wolverhampton Coun Judith Rowley (Lab Blakenhall) hit out at operator Central Trains, claiming it had never taken the service seriously.
"If ever rolling stock is needed elsewhere they take it off with little or no warning. It has never been that credible," she said.
"Patronage on the line is so low because people cannot rely on it, but the service has great potential for growth. Junction 10 of the M6 is regularly snarled up, it is the biggest car park in the West Midlands."
WMPTA member Paul Tilsley (Lib Dem Birmingham Sheldon) said: "Walsall to Wolverhampton is one of the most difficult journeys in the region and if the service had been marketed properly we could have taken thousands more cars off the roads."
A Central Trains spokesman said Centro, the passenger transport promoter and WMPTA's own executive arm, was responsible for marketing the line. But he accepted that the introduction of buses replacing trains on the line since January, because of an industrial dispute with train drivers, had contributed to the low patronage.
"We expect passenger numbers to go up dramatically when trains are reinstated on June 13. However, I would stress that it is still the least popular line on the West Midlands commuter network."
The route was introduced in 1998 as a franchise commitment after Central Trains' parent company National Express successfully bid for the West Midlands franchise.
Walsall Borough Council has passed a cross-party resolution to oppose the SRA plan, which is part of its West Midlands Route Utilisation Strategy consultation document.
Consultation closes next month.