South West MPs from all three main political parties are raising concerns over the future of the rail system in the region.
Cutting the overnight train is the thin end of the wedge fear MPs
The government will shortly be awarding new franchises to train operators who run the services in Devon and Cornwall
The Strategic Rail Authority says some services should be axed and bidders should offer alternatives to the overnight sleeper to and from London.
The government says that at the moment the service is not cost effective.
Devonport Labour MP Alison Seabeck, Liberal Democrat MP for Falmouth, Julia Goldsworthy, and Conservative MP for Totnes, Anthony Steen, say that train transport to the West Country is essential to the region's economy.
Ms Seabeck said: "The whole South West is an area which has desperately been trying to regenerate itself and Plymouth is beginning to grow."
Ms Goldsworthy said: "We need business people who use that train and businesses are desperate for that service to be retained."
"People go to London for face to face meetings. Newquay airport is under threat and the roads are blocked during the summer months.
"Trains are the only alternative for many businesses."
She added: "We are concerned that this is the thin end of the wedge. In the next franchise are they going to ask for services west of Plymouth to be costed separately?
"What happens when the Tamar Bridge reaches the end of its lifespan?"
Mr Steen: "This is all about money. The government wants more money for its licences and it believes it can get more money for its overnight services."