Nearly 2,000 miners across four states may lose their jobs after yet another major coal company filed for bankruptcy this week – the third since May and fourth since last October.

The bankruptcy filing from Revelation Energy LLC and its affiliate Blackjewel LLC, the nation's sixth-top coal producing company in 2017, comes amid President Donald Trump's ongoing efforts to boost the flagging industry.

The Trump administration rolled out a rule last month aiming to extend the lives of aging coal-fired power plants across the nation. Environmentalists say the Affordable Clean Energy rule would trigger premature deaths, including from lung disease.

During his 2016 presidential campaign, Trump promised to revitalize coal and save miners' jobs, despite scientists linking the burning of the fossil fuels to global warming, but the industry has continued to suffer losses.

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At mines and facilities in Virginia, Kentucky, West Virginia and Wyoming, Revelation Energy and Blackjewel employ 1,800 workers, according to court documents and The Casper (Wyo.) Star-Tribune. Company officials estimate they owe $156 million for goods and services, West Virginia Public Radio reported.

Last month, Cambrian Coal LLC also filed for bankruptcy. The company operating in Kentucky and Virginia blamed its bankruptcy on changes in demand and regulations related to the Clean Air Act.

Another coal-producing leader filed for Chapter 11 bankruptcy in May. Once the nation's third-largest coal company, Wyoming-based Cloud Peak Energy employed 1,300 people at the time of its filing. It accounted for 7.4% of total U.S. coal production in 2017, according to the Department of Labor.

And, the nation's ninth-leading coal company went to bankruptcy court late in 2018. Colorado-based Westmoreland Coal Co. had more than $1.4 billion in debt at the time, The Associated Press reported.

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Although Trump has touted coal's rebirth, 51 coal plants have closed and eight coal companies have filed for bankruptcy since his election, CBS News reported last month.

Coal’s share of the U.S. electricity mix fell from 48% in 2008 to 27% in 2018 and is projected to be 22% in 2020, according to the Department of Energy.

“We’re retiring a coal plant every month. Coal will all be gone by 2030,” said Bruce Nilles, a managing director at the Rocky Mountain Institute, a think tank in Colorado that focuses on energy and resource efficiency.

Coal policy, including Trump's Affordable Clean Energy rule, could influence the 2020 election in swing states where coal is still mined, such as Ohio and Pennsylvania.

Contributing: Beth Weise and Ledyard King, USA TODAY