On April 17, several environmental groups and states sent a 60 day notice of their intent to sue the Environmental Protection Agency (EPA) for missing the April 13 final rule deadline for a regulation involving new fossil fuel-fired plants. The rule involved new source performance standards for carbon dioxide emissions. The states intending to sue are Connecticut, Delaware, Maine, Massachusetts, New Mexico, New York, Oregon, Rhode Island, Vermont, and Washington. The Environmental Defense Fund, the Natural Resources Defense Council, and the Sierra Club are the environmental groups considering challenging the EPA. In addition, New York City and Washington, D.C. are also intending to sue.