A major American coal mining empire is now seeking bankruptcy protection despite a volley of regulatory breaks pushed - and received - from the Trump administration by its chief executive officer.

Murray Energy, based in Ohio, filed for Chapter 11 bankruptcy late Tuesday, joining a growing list of embattled miners as the firm makes a detour from coal to cheaper, less polluting renewable energy.

The filing represents a major political setback for US President Donald Trump, who as a central part of his campaign and early administration had sought to end what he termed as Democrats' "war on coal."

According to the Energy Information Administration, Murray Energy was the fourth largest coal producer last year, accounting for over 6 percent of total production.

Other major producers, including Blackjewel Mining in West Virginia and Cloud Peak Energy in Wyoming, have sought bankruptcy protection as well, this year.

Murray Energy's transformation, said former chief executive officer Robert Murray, is crucial to access cash and best position itself for long-term survival.

The operations of the coal giant cover Georgia, Indiana, Kentucky, Missouri, Ohio, Washington, West Virginia, South America, and Colombia.

According to Cecil Roberts, president of United Mine Workers of America, the government's preference for gas and renewable energy to scrap coal-fired power generation, combined with a recent sharp reduction in coal exports, provided a one-two punch that a cash-strapped Murray Energy could not deal with.

West Virginia Senate President Mitch Carmichael disclosed that the announcement for a major revamp came as a huge surprise even with the mounting challenges in the coal business, noting that he is concerned about the pensions of nearly 7,000 employees of Murray Energy.

Democrat-Senator Joe Manchin, from West Virginia, said on Twitter that the company had to vow to meet its commitments to provide coal workers with pension protection.

The group had made public that it was not resistant to market disruptions when it announced that its creditors were shying away from loans.

West Virginia University research assistant professor Brian Lego divulged that such heavy company restructuring scheme could add more burden to an already battered economy.

As chief executive officer, Murray was resistant to filing bankruptcy, condemning many coal companies who wanted to streamline in recent years.

He lamented the series of bankruptcy filings in the coal market and how its competitors were able to re-enter the market, during a 2016 interview with The Associated Press.

Murray, who was succeeded by Robert Moore as top boss on Tuesday, has linked his fortunes with Trump. In July, he hosted a president's fundraiser that was expected to raise $2.5 million.

He has also flexed his leverage at the local level, contributing thousands of dollars to West Virginia Gov. Jim Justice's 2020 bid and lobbying effectively for a steam coal tax cut in the economically depressed Mountain State.