Republicans have declared war on what they call President Obama’s “war on coal.”

House Natural Resources Committee Republicans on Friday escalated their year-long investigation into the Obama administration’s planned rewrite of coal-mining regulations imposed by President George W. Bush.

Committee Chairman Doc Hastings (R-Wash.) released internal Interior Department documents that he said showed the toll the planned regulations will take on the economy.

“Thousands of jobs, American energy production and the economic livelihoods of communities across the country will be impact by this regulation,” Hastings said Friday during a press conference in the Capitol. “The stakes are extremely high.”