The Obama administration will seek to cut greenhouse gas emissions from existing power plants 30% from 2005 levels by 2030, potentially one of the biggest steps any country has taken to confront climate change, people familiar with the plan said Sunday.
Seen as the linchpin of President Obama's climate campaign and a key part of his domestic policy legacy, the proposed power plant rule would set state-specific targets for carbon dioxide reductions and let local officials decide how best to meet the goals.
The proposal by the U.S. Environmental Protection Agency is intended to limit air pollution by carbon dioxide, a gas that traps heat in the atmosphere and drives global warming.
The complex rule, which will be officially announced Monday, faces a yearlong comment and review period. It is certain to spark a high-stakes legal and political battle that will echo through the November midterm election and beyond.
Opponents — including the U.S. Chamber of Commerce, the mining industry and congressional Republicans and Democrats from coal-producing states — have already lined up against it. Critics labeled it government overreach that would do little to reduce climate change while costing tens of billions of dollars and thousands of jobs.
"Now the president is once again looking to do through regulation what he couldn't accomplish through legislation. But myself and others are sounding the real alarm of how the president's plan will be dangerous for our economy and future job opportunities," said Sen. James M. Inhofe (R-Okla.), citing a U.S. Chamber of Commerce report that estimated the rule could cost the economy $50 billion annually.
But environmental groups and other administration allies applauded the proposal as crucial to efforts to cut the single greatest source of greenhouse gases. Power plants account for an estimated 40% of all carbon dioxide emissions in the country.
Sen. Brian Schatz (D-Hawaii), who took part in a conference call with Obama and other key officials late Sunday, praised the plan because it gives states and regions flexibility to meet the emission targets.
"This allows economies to adjust and transform over time in a very aggressive way but a very realistic way," said Schatz, who has made climate change a signature issue since he joined the Senate in 2012.
"This is becoming a consensus, rational position for people of all parties across the country," Schatz said. "Republicans are on the wrong side of history here. That's going to become clear not just over the long run but over the next couple of elections."
The rule would allow states to offset their carbon emissions by developing other parts of the power grid, including greater energy efficiency or increased use of renewable energy, such as wind and solar.
"The reality of it is that we will have to build and invest in renewables," said Lisa Bonnett, director of the Illinois Environmental Protection Agency.
The 30% cut will be based on 2005 emission levels, which were 10% higher than in 2012. The decline stems from the recent boom in cleaner-burning natural gas, which has displaced a great deal of coal as a fuel source.
In addition, different states would have different targets, based on their fuel mix.
States that burn a lot of coal would begin their reductions from a higher emissions level than those that burn natural gas, which emits less carbon dioxide.
Because the rule has not been officially issued, the 30% reduction could be one of several options the EPA presents for public comment, environmentalists said.
Obama telephoned a group of Senate and House Democrats to thank them for their support in advance of Monday's announcement by Gina McCarthy, head of the EPA.
If enacted, the rule would make good on a pledge Obama made last year to tackle climate change through his executive authority in the face of congressional inaction on the issue.
Domestic opponents of unilateral U.S. action argue that climate change is a global problem that requires emissions cuts from all major polluters, especially newly industrializing giants China, India and Brazil.
The rule's backers say a strong curb on greenhouse gas emissions could give U.S. negotiators more leverage at the next major United Nations meeting to address climate change, scheduled for 2015 in Paris.
Michael Brune, executive director of the Sierra Club, said an ambitious U.S. carbon standard would lead to "stronger agreements for similar reductions from China, India and Brazil."
Christiana Figueres, executive secretary of the U.N. Framework Convention on Climate Change, seemed to agree.
"The decision by President Obama to launch plans to more tightly regulate emissions from power plants will send a good signal to nations everywhere that one of the world's biggest emitters is taking the future of the planet and its people seriously," she said in a statement. "I fully expect action by the United States to spur others in taking concrete action."
Obama pledged after he was first elected that, by 2020, the U.S. would cut its greenhouse gas emissions 17% from 2005 levels.
But in mid-2010, Congress defeated an ambitious package of "cap and trade" climate change measures that would have imposed deep cuts on the production of greenhouse gases.
Since then, nearly all congressional Republicans and some Democrats from fossil-fuel-producing states have denied that human activity is behind the rapid warming of the planet.
As a result, the White House retooled its climate strategy in the second term to bypass Congress with piecemeal measures.
Although the carbon standard is the most sweeping, it's not the first.
In September, the EPA proposed rules to curtail greenhouse gas emissions from new power plants. The stringent limits, which will be completed in January, would all but ensure a halt in new construction of coal-fired plants.
This year, the administration announced tougher fuel economy standards for heavy-duty, long-haul trucks that complement existing fuel efficiency rules for cars and light trucks.
Evan Halper, Michael A. Memoli and Kathleen Hennessey in the Washington bureau contributed to this report.