Union leaders are joining the growing chorus of opposition to the “war on coal” being waged by President Obama through the Environmental Protection Agency.

Raymond Ventrone, who represents more than 2,000 members of the Boilermakers Union in Western Pennsylvania, Ohio and West Virginia, voiced his opposition to the EPA’s latest coal regulations in a letter to the editor in the Pittsburgh Post-Gazette.

Ventrone said that he and his fellow boilermakers helped install EPA-approved pollution-control equipment at a coal-fired power plant three years ago. But now, those upgrades have been “deemed insufficient by the very same agency by virtue of new regulations created without a vote in Congress or input from the public,” Ventrone said.

According to Ventrone, two coal plants in his area will be closing due to the EPA’s regulations — a loss of 400 jobs in southwestern Pennsylvania. Those two coal plants are among the 207 plants that will close in the next decade due to conversions to natural gas and EPA regulations.

Ventrone also said that the EPA’s goal is not cleaner air but eliminating coal, because even though coal usage has tripled, the presence of pollutants has decreased 56 percent. “We can have clean air and keep coal as a vital part of our economy,” Ventrone said.

The boilermakers union is hardly a friend to conservatives. The union sponsored an ad in 2010 attacking the GOP for everything from the financial crisis to Hurricane Katrina. But after the 2010 midterm elections, the union’s lock-step support of Obama began to crumble. Boilermakers, along with utility and mining unions, wrote a letter to the EPA in March 2011 warning of “significant job losses across the country.”

Obama’s war on coal has been a politically sensitive issue for him because it pits his administration and environmentalists against another of his core constituencies: labor unions. Stuart Stevens wrote for the Daily Beast that those “coal-country families are largely union members or union-friendly, and they historically have been more Democratic than Republican.”

Ventrone wrote that the boilermakers have been vilified by opponents of coal and have even been called “murderers.” He wrote that the war on coal is a “war against our jobs.”