The EPA will launch the most dramatic anti-pollution regulation in a generation early next month, a sweeping crackdown on carbon that offers President Barack Obama his last real shot at a legacy on climate change — while causing significant political peril for red-state Democrats.

The move could produce a dramatic makeover of the power industry, shifting it away from coal-burning plants toward natural gas, solar and wind. While this is the big move environmentalists have been yearning for, it also has major political implications in November for a president already under fire for what the GOP is branding a job-killing “war on coal” and promises to be an election issue in energy-producing states such as West Virginia, Kentucky and Louisiana.

The Environmental Protection Agency’s proposed rule is aimed at scaling back carbon emissions from existing power plants, the nation’s largest source of greenhouse gases. It’s scheduled for a public rollout June 2, after months of efforts by the administration to publicize the mounting scientific evidence that rising seas, melting glaciers and worsening storms pose a danger to human society.

“This rule is the most significant climate action this administration will take,” said Kyle Aarons at the Center for Climate and Energy Solutions, one of a host of groups awaiting the rule’s release. Sen. Sheldon Whitehouse (D-R.I.) has urged the EPA to “go ahead boldly” with the rule, saying the agency must step in where Congress has refused to act.