The Government is considering an upgrade of the Great Western line to run electric trains further west amid calls from a Westcountry MP to electrify the line from London to Penzance.
Faster and more efficient electric trains do not run beyond Newbury, Berkshire.
But in the House of Commons yesterday, Transport Minister Stephen Hammond admitted there was a "very good business case" for ditching diesels on a further 14 miles of line between Newbury and Bedwyn, and that a report into going further is "being considered".
The revelation emerged following a question from Torbay MP Adrian Sanders, who said electrifying the line between the capital and west Cornwall would cost a fraction of the £50 billion to be lavished on the HS2 north-south line.
The Lib Dem MP's call comes amid track bosses Network Rail studying at least five new rail links in Devon to provide a backstop to the collapsed mainline at Dawlish.
Some politicians and business leaders disagree on how to make the region's rail service more reliable, with Mr Sanders among those warning an alternative new route across Dartmoor via Okehampton would damage the South Devon economy.
During Transport Questions, Mr Sanders said: "Will the Minister commit to looking at the electrification of the Penzance to Paddington route, a scheme which, at a fraction of the cost of HS2, would benefit everyone in the South West, unlike some of the other promoted schemes that would benefit only some people at the expense of others?"
In reply, Mr Hammond said the Department for Transport commissioned a study from Arup in 2012 to look at electrification to the west of Newbury.
He said: "We have already seen some of that study's results, which indicate that there is a very good business case for going to Bedwyn, and further results from that study are being considered by the department."
The Great Western line is already to be electrified to Bristol. But most trains to west Somerset, Devon and Cornwall run on the "second" line via Newbury.
Earlier in the question session, Mel Stride, Conservative MP for Central Devon, pressed Transport Secretary Patrick McLoughlin to take "very seriously" the proposal for a new railway line from Exeter to Plymouth via Okehampton and Tavistock.
Mr McLoughlin replied: "I have asked Network Rail to do a substantive piece of work, which I expect to get this July and which will address some of the options."
Alison Seabeck, Labour MP for Plymouth Moor View, added the South West "deserves better", claiming there was "nothing" in the Budget for road or rail transport and the delayed new Great Western franchise is a "dog's breakfast". She urged the Secretary of State to press Chancellor George Osborne to ensure that commitments for finance for investment will be made either before or during the autumn financial statement.