Work on the electrification of the Midland Mainline has been halted by the Government.
Officials in market Harborough described the decision and “concerning” which may have “potentially serious outcomes” for the town and region.
The move comes after Network Rail admitted it had been “overly optimistic” about completing the five-year, £38bn plan.
Transport Secretary Patrick McLoughlin responded by announcing that the plan was being “reset” because it was “costing more and taking longer”.
He told MPs that electrification work was being “paused” on the Midland Mainline, which is the line through Corby, Kettering and Wellingborough, and on the Transpennine route between Leeds and Manchester.
Cllr Phil Knowles, Harborough district councillor and chairman of the Liberal Democrats East Midlands, said: “The programme and the promises were laid out and seemingly moving forward.
“Now it seems this multi-billion pound scheme is set to come in over budget and much delayed.
“When will the scheme be completed?
“How much over budget is anticipated and importantly, can we have cast iron assurances that all of the long awaited parts of the scheme will actually be delivered?
“I am sure my worries and questions will be echoed by a considerable number of people as the news spreads.
“Will the delay in delivering the scheme impact negatively on those who are considering investing in the East Midlands?
“Our region has so much to offer and does not deserve yet another disappointment.”
More reaction on this in the next edition of the Harborough Mail.