"For power producers and coal mining companies that reject these standards, they have no reason to complain, and every excuse to innovate," said Sen. Ed Markey, D-Mass., the author of a 2009 bill to limit global warming. The legislation, backed by the White House, passed the House, but died in the Senate.A powerful Republican opponent of the EPA plan, Senate Minority Leader Mitch McConnell of Kentucky, said in an emailed statement that "the president is leading a war on coal." The regulations have been in the works since 2011 and stem from a 1970 law passed by Congress to control air pollution. In 2007, the Supreme Court ruled that that law, the Clean Air Act, could be applied to heat-trapping pollution. The EPA already has issued rules aimed at curbing global warming pollution from automobiles and the largest industrial sources. An EPA official told the AP that the rule doesn't specify any particular technology. But the official acknowledged that carbon capture was the only current technology available for a company to meet the threshold of 1,100 pounds of carbon dioxide emissions per megawatt hour of electricity. To put that in perspective, a modern coal plant without carbon controls would release about 1,800 pounds per megawatt hour. The official spoke on condition of anonymity because the announcement of the rule had not been made. The administration went back to the drawing board after receiving more than 2 million comments on its first proposal, which was legally vulnerable because it required coal and natural gas to meet the same limit. Coal and natural gas now have separate standards, but the latest proposal will almost certainly to be litigated once it becomes final, which the law requires the EPA to do in a year. The legal argument likely will be based around whether carbon capture and storage is a demonstrated technology.