To meet the standard, newly built coal-fired power plants must install expensive carbon capture technology (CCS) and bury it underground. Largely owing to high costs, no coal-fired power plant has taken such steps yet. But between ongoing attacks from Washington and a natural gas boom in North America, coal has already been on the defensive.

By reorienting American power supplies from traditional fossil fuels to less-established renewables, moreover, President Obama has decried what he called “the limitless dumping of carbon pollution” from the power plants that supply more than 40% of America’s energy.

The proposed rule won’t immediately impact current operations, according to Beltway officials. Over the long term, however, it would enable the government to curb existing power plant fleet emissions. So far, Obama has allowed the Environmental Protection Agency (EPA) until Q3 2014 to propose the regulations.

Leaders industry wide and House Republicans, like Mitch McConnell of Kentucky, slammed the proposal. “The administration has been waging a war on coal and Kentucky jobs,” the Senate minority leader said in an e-mail to Bloomberg News. Obama’s “latest proposal is not only an open war on coal jobs, but on all the residents, jobs and businesses across the commonwealth that rely on this vital industry.”

Natural gas, on the other hand, faces no extra pollution controls, according to the pending regulatory rules.

In the works since 2011, the proposal stems from a 1970 Congressional law to control air pollution emissions. Later, in 2007, the Supreme Court justices ruled that the Clean Air Act could be applied to heat-trapping pollution. By then, the EPA had already mandated regulations to curb emissions from cars and the large-scale industrial energy sources.

Legal arguments will focus on the true effectiveness of carbon capture and storage, according to mining industry representatives. “The EPA has set a dangerous, far-reaching precedent for the broader economy by failing to base standards on reliable technology,” said National Mining Association (NMA) President and CEO Hal Quinn. The EPA regulation, he added, “effectively bans coal from America’s power portfolio.”

Indeed, the consequences for an already ailing economy could be catastrophic. “By forcing power plants to abandon the nation’s largest, most reliable source of affordable electricity,” he added, the EPA is “recklessly gambling with the nation’s energy and economic future.”