The Environmental Protection Agency on Friday unveiled the first-ever curbs on carbon emissions at new power plants, setting the stage for a fierce legal and political battle over President Obama's far-reaching green energy agenda.

EPA Administrator Gina McCarthy outlined proposed rules that would require new coal plants to employ carbon-capture technology. The proposal does not apply to existing power plants. New standards for existing plants are due next June.

But McCarthy on Friday launched the latest salvo in a battle with Republicans who contend Democrats are engaging in a “war on coal” and fear the administration's green push will hurt the economy.

“The overwhelming judgment of science tells us that climate change is real and that human activities are fueling that change,” McCarthy said Friday in a speech at the National Press Club. “We must take action. … We all know this isn't just about melting glaciers.”

Under the regulations, new coal-fired plants are required to capture roughly 40 percent of their carbon-dioxide emissions.

McCarthy called the benchmarks “flexible and achievable” and said the standards had been crafted after extensive consultation with states and industry advocates.

Still, some energy producers say such goals are unrealistic and will lead to the shuttering of coal power plants, which produce about 40 percent of U.S electricity. And the measures will certainly be challenged in court.

"If energy has been the one bright spot in the U.S. economy, then the regulations unveiled by the EPA today aim to dim it and jeopardize our gains,” National Association of Manufacturers President Jay Timmons said. “In this latest overreach, the EPA is regulating greenhouse gases under a statute never designed for this purpose. Maybe that’s the mandate from above.”

Red-state Democrats were also quick to blast the EPA plan.

"Today’s announcement of the EPA’s new source performance standard is direct evidence that this administration is trying to hold the coal industry to impossible standards," Sen. Joe Manchin, D-W.Va., said. "Never before has the federal government forced an industry to do something that is technologically impossible."

McCarthy, who has spent years developing the landmark EPA rules, sought to downplay such criticisms.

“I believe this proposal, rather than killing future coal, actually sets out a certain pathway forward for coal to continue to be part of the diverse mix in this country,” she insisted.

Rebuffed by a GOP-controlled House with little incentive to budge on climate change, Obama has decided to go it alone on fighting warming temperatures. Rather than presenting lawmakers with a legislative plan to cap carbon emissions, Obama is turning to his EPA to implement the most extensive environmental regulations in decades.

At the core of Obama's environmental push are tighter rules for power plants, more energy-efficient buildings and appliances, and additional green energy development on public lands.

For environmentalists, tougher restrictions on current coal-burning power plants have long been viewed as the crown jewel of their agenda, but it's also an objective likely to stoke GOP charges of presidential overreach.

On Friday, McCarthy framed her argument not just in moral terms, but said there is an economic prerogative for embracing more green technologies.

“Fighting climate change just makes good business sense,” McCarthy said, dismissing those who thought the “sky was falling.”

“All we need is the courage to act,” she added.