UPDATE 2-U.S. likely to delay climate rule on new power plants -report

(Adds administration comment in paragraph four, NRDC comments in final three paragraphs)

WASHINGTON, March 15 (Reuters) - U.S. environmental regulators will likely delay finalizing rules to limit carbon emissions from new power plants, a measure that has been one of President Barack Obama's top strategies to fight climate change, the Washington Post reported on Friday.

The rules were proposed by the Environmental Protection Agency (EPA) nearly a year ago. They are expected to be revised to set a separate standard for coal-fired plants, as opposed to natural-gas-fired plants, the newspaper said.

The administration had been expected to tackle emissions from existing power plants, which are responsible for a much larger volume of U.S. emissions, up to 40 percent, after finalizing the rules on new plants.

An administration official said the report was not accurate because the EPA was still working on the rule. The official did say that sifting through the massive volume of comments was time-consuming.

According to the EPA's regulatory tracker, the so-called greenhouse gas "New Source Performance Standard" for new power plants was projected to be finalized by the end of this month.

But EPA Administrator nominee Gina McCarthy, who was in charge of EPA rules as assistant administrator for the agency's office for air and radiation, hinted last month that finalizing the proposal may take extra time since it had received nearly 2 million comments on the rules.

McCarthy will face a Senate confirmation hearing in April, Capitol Hill sources said, and is expected to get pushback from lawmakers from states that are heavily reliant on coal.

The EPA proposal says new plants can emit no more than 1,000 pounds of carbon dioxide per megawatt-hour, a standard that effectively blocks construction of new coal-fired plants.

David Doniger, policy director of the Natural Resources Defense Council's climate and air program, said he has no evidence that the EPA plans to weaken the current proposal but warned that a deadline to finalize the rule is less than one month away.

"If they don't meet the deadline, environmental organizations will start taking the legal steps to get a court to force the deadline," he said.

He added that the EPA holds regular, informal consultations with various stakeholders including green groups and electric utilities to hear proposals for setting an emissions standard from existing power plants.

(Reporting by Timothy Gardner and Valerie Volcovici; Editing by John Wallace and Dale Hudson)