The Obama administration is leaning toward revising its landmark proposal to regulate greenhouse gas emissions from new power plants, according to several individuals briefed on the matter, a move that would delay tougher restrictions and anger many environmentalists.

The discussions center on the first greenhouse gas limits for power plants, which were proposed by the Environmental Protection Agency nearly a year ago. Rewriting the proposal would significantly postpone any action and also might allow the agency to set more permissive standards for coal-fired power plants, which are roughly twice as polluting as those fueled by natural gas.

Any retreat on the rules would be a blow to environmental groups and their supporters, who constituted a crucial voting bloc for President Obama and other Democrats in last year’s election.

White House spokesman Clark Stevens said suggestions of any sort of decision by the EPA was incorrect, noting the agency was still in the process of reviewing the 2 million comments it had received on the rule.

The move coincides with Obama’s call on Friday for a new federal fund to research clean energy alternatives for cars and trucks. The creation of an Energy Security Trust, which the president outlined in his State of the Union speech, would invest $2 billion in federal revenue from oil and gas leasing into breakthrough technologies.

“After years of talking about it, we’re finally poised to take control of our energy future,” Obama said.

The contrast between the two policies highlights the delicate balancing act Obama is attempting to strike in his second-term energy and environmental agenda — seeking ways to combat climate change, while avoiding damage to a still-struggling economy.

“It really is a tension between short- and long-term goals,” said Joshua Freed, vice president for the Clean Energy Program at the liberal think tank Third Way. “Actions need to be taken now both on climate and clean energy that require sometimes painful transitions from some fuel sources to new technology and new sources that either may not be ready yet or require some dislocations.”

Ross Eisenberg, vice president of energy and resources at the National Association of Manufacturers, said the options available to the administration to combat greenhouse gas emissions “are not particularly good.”

Rep. Ed Whitfield (R-Ky.), who chairs the Energy and Commerce Subcommittee on Energy and Power, was scathing in his assessment of the president’s approach to energy policy. “It’s being set by fiat by this administration,” Whitfield said in an interview, adding that when it comes to curbing greenhouse gas emissions from new power plants, “the consequences of this are gigantic. I don’t think the American public understands how gigantic they are.”

“As far as I know, America is the only country in the world where you can’t build a new coal plant because we don’t have the technology to meet those standards,” he said.

The Energy Security Trust would be just one component of the president’s broad “all-of-the-above” energy strategy, which includes supporting such alternative energies as wind, solar and geothermal sources, as well as increasing oil and gas development in the United States.

Obama, who noted that breakthrough research into advanced battery technology took place at Argonne National Laboratory outside of Chicago, said new investments in clean energy research are critical to maintaining the United States’s competitive edge with countries such as China, Japan and Germany.

The administration anticipates the federal government will reap a growing amount of royalties in the coming years because of growth in oil and gas drilling. Obama said the Energy Security Trust would not add “a dime to our deficit.”

But congressional Republicans, whose support would be critical to establishing the trust, appeared skeptical of Obama’s proposal. A spokesman for Sen. Lisa Murkowski (Alaska), the ranking Republican on the Energy and Natural Resources Committee, said Obama “hit on a good idea” with the Energy Security Trust. But the spokesman, Robert Dillon, criticized the plan because it would divert shares of existing royalties and “would not enable new energy production to pay for it.”

The EPA proposal, which is due to be finalized April 13, would require any new power plant to emit no more than 1,000 pounds of carbon dioxide per megawatt hour of electricity produced.

Standards for new power plants are less controversial than imposing carbon limits on existing plants, which emit 2.2 billion tons of carbon dioxide a year, or 40 percent of the nation’s carbon output. The administration has yet to say if it will pursue that policy.

“Any signal they’re stalled just ensures further delay in confronting climate change at a time when the Americans are looking for momentum,” Larry Schweiger, president and chief executive of the National Wildlife Federation, said in a statement. “We’re now in the fifth year of the Obama administration and industrial carbon pollution remains unregulated. When it comes to climate-disrupting carbon pollution, coal-fired power plants are still allowed to treat America’s skies like an open sewer, free of charge.”

Individuals familiar with the power plant discussions spoke on the condition of anonymity because a final decision has not been made.

Beyond power plant regulation, Obama is also under pressure from environmentalists to reject a permit for the Keystone XL pipeline, which would transport heavy crude from Alberta’s oil sands to Gulf Coast refineries. As the president headed to the airport Friday, about two dozen protesters stood on the side of the road outside Argonne holding handmade signs saying, “No on XL.”

Obama deputy press secretary Josh Earnest told reporters traveling on Air Force One that activists have overestimated the impact of the project. “Thousands of miles of pipelines have been built since President Obama took office inside the United States of America, and it hasn’t had a measurable impact on climate change,” Earnest said. “But what has had an impact, measurable impact on climate change has been, for example, the car rule that the president has put in place that has greatly increased fuel efficiency and reduced carbon emissions. . . . Those are the kinds of things that we can do to address the challenge of climate change.”

Rucker reported from Lemont, Ill.

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