A major initiative to cut the pollution emitted from the nation's power plants set off a scramble Monday in Washington - where Republicans instantly pounced on the proposed rules - and in states, where much of the work in implementing the rules will be done.
In many states, the move away from carbon-heavy coal to cleaner sources of energy is already underway, and those states could have an easier time adapting to new rules proposed Monday by the federal government.
Other states - those in the Rust Belt, for example - still are heavily dependent on coal to produce electricity. Those states might struggle.
"Utilities that have large holdings in the West are going to be generally well-positioned," said Michael Brune, executive director of the Sierra Club, an environmental group. Other states, such as Iowa, have big wind production already on line. Still other states - California, for example - already have worked to reduce emissions.
Brune noted that many of the alternatives to coal-fired power plants are becoming more affordable: Wind and solar power, for example, are options that can help states switch the mix of their power from dirtier to cleaner technology.
"States that have already done a lot will still have to do more," he said. "And states that haven't done much will have to do a whole lot more - and they will be given more time in which to do it."
Under the rule unveiled Monday by the White House and the Environmental Protection Agency, states will have specific goals to reduce carbon pollution and will be given wide flexibility in how to reach those goals. States can use a mix of power sources, energy efficiency and demand-side management to meet the goals. They can work with other states to develop multi-state plans, or they can work alone.
On a conference call hosted by the American Lung Association, President Barack Obama said the plan would curb electricity prices and protect the health of Americans, including children who suffer from breathing disorders such as asthma.
He predicted a "heated debate" with critics who say the guidelines will cost the U.S. jobs, but he said previous claims have been debunked.
"When Americans are called on to innovate, that's what we do," Obama said, noting advances in combating acid rain and in developing fuel-efficient cars and appliances.
"There's going to be a lot of efforts to put out misinformation and try to make sure that spin overwhelms substance and spin overwhelms science," he said.
Obama touted the regulations as a "sensible state-based plan" that gives states a "wide, wide range of options" to achieve their goals.
The overall goals are for the nation as a whole. By 2030, the White House and the EPA said, the actions will help cut carbon emission from the power sector by 30 percent below 2005 levels, "which is equal to the emissions from powering more than half the homes in the United States for one year."
Doing so, the administration said, will cut particle pollution, nitrogen oxides and sulfur dioxide by more than 25 percent, allowing the nation to avoid premature deaths and asthma attacks in children. It will result in fewer missed school or work days, the administration said, and will shrink electricity bills roughly 8 percent.
The state-by-state goals were developed after examining each state's mix of power sources. In Florida, for example, the EPA is proposing that state officials develop a plan to lower the carbon pollution rate by 38 percent.
In Iowa, which already produces 25 percent of its power from wind, the carbon reduction goal is 16 percent; in South Carolina, the goal is a reduction of 51 percent.
The EPA said the intention is not to put requirements on individual power plants. It will be up to Florida, Iowa or South Carolina officials to choose the best way to achieve the overall reductions.
The process will be strung out over several years, with comments on the proposed rules coming in for the next four months, initial plans due from states by mid-2016 and extensions pushing some state plans back to 2017 or 2018.
In between now and those dates, however, will be two elections. And the proposed rules already have engendered a huge political backlash.
The effort reflects a major unmet priority for Obama, who promised upon taking office that he'd "work tirelessly ... to roll back the specter of a warming planet." It's also popular with his liberal base, which has pressed the administration to be much more aggressive on environmental issues.
Obama needs those voters to turn out in November if Democrats are to retain control of the Senate.
But the rules pose a risk, particularly for Senate Democrats running for re-election in conservative-leaning states, by delivering a campaign-ready message for Republicans, already hammering Obama's environmental regulations as a "war on coal" and a burden on businesses trying to create jobs.
Sen. Marco Rubio, R-Fla., said that "the largest contributors of carbon to the atmosphere today are developing countries like China and India" and added that, "Americans are going to pay a terrible price for these sorts of unilateral executive actions the president is taking on energy."
Senate Minority Leader Mitch McConnell, R-Ky., pronounced the regulations "a dagger in the heart of the American middle class, and to representative Democracy itself."
His Democratic challenger in a heated Senate race this year, Alison Lundergan Grimes, sought to distance herself, promising that if elected she'd "fiercely oppose" what she called Obama's "attack on Kentucky's coal industry."
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