But EPA and other backers of the rules say they will offer huge public health benefits and help to tackle climate change at a minimal cost.
The rules, which EPA is issuing under a settlement with environmentalists and several states, have been delayed repeatedly.
“Our timeline has been for the end of January. We think we are close to that timeline," Gina McCarthy, EPA’s top air quality official, said Jan. 19.
EPA spokesman Brendan Gilfillan said Thursday that “EPA is on track to propose [greenhouse gas] standards for new power plants early this year."
“We continue to work with OMB through the interagency review process and will issue the proposal when that review is complete."
OMB’s website shows that power industry officials have held a suite of meetings with OMB staff in February. Environmentalists backing the rules have also met with the office this month.
Coal-fired power plants are a huge source of greenhouse gas emissions, which the vast majority of the world's scientists blame for climate change.