WASHINGTON — Ongoing rail service problems have left power plants from Minnesota to Texas low on coal as an early blast of winter weather hit the nation’s midsection this week.

Some fear the stage has been set for a repeat of last winter, when heavy snowfall and subzero temperatures crippled rail operations in the Upper Midwest and Chicago, which had ripple effects across the rest of the country.

Anticipating heavy electricity use this winter, coal customers and groups representing them have written letters to federal regulators to complain about delayed deliveries and low stockpiles.

“Our members are having a hard time receiving the coal they need to operate their plants,” said Will Coffman, senior government relations representative for the American Public Power Association.

Last year’s problems have become this year’s problems as overall rail traffic rises to levels not seen since before the last recession and railroads struggle to handle large volumes of grain, coal, automobiles and increasingly, crude oil.