"I know people are wondering: Can we cut pollution while keeping our energy affordable and reliable? We can, and we will," said EPA Administrator Gina McCarthy.
Turning to the four-decades-old Clean Air Act, the EPA is giving customized targets to each state, then leaving it up to those states to develop plans to meet their targets. Some states will be allowed to emit more and others less, leading to an overall, nationwide reduction of 30 percent.
West Virginia, for example, must reduce the pollution it puts out per unit of power by 19 percent compared to 2012. Ohio's target is a 28 percent reduction, while Kentucky will have to find a way to make an 18 percent cut.
On the other extreme, New York has a targeted reduction of 44 percent. But New York already has joined with other Northeast states to curb carbon dioxide from power plants, meaning it's further along than many other states. The EPA said states like New York wouldn't be punished for being proactive.
Although Obama initially wanted each state to submit its plan by June 2016, the draft proposal shows states could get extensions until 2017. If they join with other states, as New York has done, they could have until 2018, kicking full implementation of the rules well into the next president's administration.
That raises the possibility that shifting political dynamics in Washington could alter the rule's course. Although Obama could veto action by Congress to block the rule, he can't ensure that his successor will do the same.
A few Democrats joined a chorus of Republicans in vowing to obstruct the rules legislatively. Rep. Nick Rahall, a vulnerable West Virginia Democrat, said he would not only back legislation but also join lawsuits. Republican House Speaker John Boehner simply called Obama's plan "nuts."
Another potential hitch: governors who refuse to cooperate. If a state declines to develop a plan, the EPA can create one itself. But how EPA could force a state to comply with that plan remains murky.
The administration said the nearly $9 billion price tag will be offset numerous times over by health savings from reductions in other pollutants like soot and smog that will accompany a shift away from dirtier fuels.
To meet their targets, states could make power plants more efficient, reduce the frequency at which coal-fired power plants supply power to the grid, and invest in more renewable, low-carbon energy sources.
Associated Press writers Juergen Baetz in Brussels and Jonathan Fahey in New York contributed to this report.
Reach Dina Cappiello at http://twitter.com/dinacappiello and Josh Lederman at http://twitter.com/joshledermanAP