EPA is planning a notice of proposed rulemaking for a Federal plan to implement greenhouse gas emission guidelines for existing fossil fuel-fired electric generating units (EGUs). The emission guidelines were proposed in June 2014 as the Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units (79 FR 34830; the Clean Power Plan). This plan is part of the President's Climate Action Plan announced in June 2013 to reduce carbon emissions from the power sector by 30 percent below 2005 levels. This Federal plan serves to: 1) provide a model rule that States can tailor for implementation, and 2) set in place a plan that EPA can implement for States that do not develop their own plan. The EPA sees this Federal plan as an interim measure to ensure that congressionally mandated emission standards under authority of section 111 of the CAA are implemented until States assume their role as the preferred implementers of the emissions guidelines.