On June 2, the Obama administration unveiled its proposal for the nation’s first-ever regulations on carbon dioxide emissions from existing power plants. It’s a bold and potentially groundbreaking move that has environmentalists, public health advocates, and power plant operators mobilizing their supporters or mounting their defenses.

Each year, electric power plants emit about 2.2 billion tons of carbon dioxide -- roughly 40 percent of the nation’s total emissions. If successful, the administration’s proposed plan would reduce this sector’s emissions to 30 percent below 2005 levels by 2030. While this goal falls a bit short of environmental advocates’ hopes, it would significantly dent one of the largest sources of carbon emissions from the world’s second-largest producer of greenhouse gases. Many hope that the United States’ action on this issue will also catalyze the international cooperation needed to address climate change on a global scale.

Critics are certain to challenge the administration’s approach in Congress and in court, and have already argued that any climate regulation is an overextension of the Environmental Protection Agency’s authority. Of course, the EPA is uniquely positioned to regulate climate pollution. The migratory nature of air pollution and climate change shakes up the borders between state and federal jurisdiction. For instance, a recent Supreme Court case debated -- and upheld -- the EPA’s ability to require states to limit soot and smog-forming air pollutants that drift into other states. Climate change presents a similar dilemma: Carbon dioxide emissions from a coal plant in Pennsylvania endanger the Florida coastline, regardless of the political and geographic boundaries between them.

But which states are most likely to contest the proposed regulations -- and why? Despite the flexibility in the regulations’ targets and tactics, some states may face steeper practical and political challenges than others. A recent review of statewide carbon emissions from the Yale Center for Environmental Law and Policy (YCELP) found that carbon pollution follows party lines. YCELP’s maps illustrate the “size” of red and blue states according to their carbon emissions. Cumulatively and on a state-by-state basis, red states tend to produce more carbon pollution than blue ones, as you can see in this map.