Even more disconcerting for the industry is the EPA guidelines that could limit greenhouse gas emissions from new power plants as early as next year.
In Ohio, Brown faces a challenge from Republican Josh Mandel, who at a recent campaign stop eagerly compared the Ohio Democrat's record on coal and energy to Manchin's. He linked Brown to the president.
"Obama is the general in the war on coal and Sherrod Brown is his lieutenant," Mandel said.
Brown defended his record in a brief interview.
"My record on energy is broad," he said. "I think as the president said, 'You look everywhere.' You start by taking away the tax breaks for the oil industry. You hear these Republicans say the president is picking winners and losers on energy and they insist on subsidizing oil, and there's no rhyme or reason to subsidize oil."
Brown wears a canary in a cage lapel pin, which he says "symbolizes to me the role of government in peoples' lives to make things better whether it's mine safety or Medicare or Social Security."
But Mike Carey, chairman of the Ohio Coal Association, doesn't see Brown as a friend of coal.
"You can have very safe miners, but if they can't mine coal, maybe they're going to be selling canaries because they're not going to be mining coal," Carey said.