U.S. Rep. George Miller of California, the senior Democrat on the House Education and the Workforce Committee, praised the Labor Department for closing loopholes that he said some mine operators have "exploited to the detriment of workers' lives and limbs."But both Miller and Sen. Jay Rockefeller, D-W.Va., called on Congress to do more and vowed to reintroduce the Robert C. Byrd Mine and Workplace Safety and Health Act this year. The legislation was first introduced in 2010, a month after the death of its namesake, the late Democratic senator from West Virginia. It was reintroduced in 2011 and revised by Rockefeller in 2012 but has languished in the Republican-controlled House. Among other things, the bill would strengthen whistleblower protections for miners who report safety concerns, increase MSHA's oversight and accountability, and give the agency tougher enforcement tools.