President Barack Obama in next week's State of the Union speech will lay out a renewed effort to combat climate change that is expected to include using his authority to curb emissions from existing power plants, people who have talked to the administration about its plans said.

The action, building on a pledge in the second inaugural address, fits within Mr. Obama's larger strategy of making full use of his executive authority in areas where Congress is putting up obstacles to his agenda.

The speech, to be delivered Tuesday, isn't finished.

Mr. Obama is likely to signal he wants to move beyond proposed Environmental Protection Agency rules on emissions from new power plants and tackle existing coal-fired plants, people familiar with the administration's plans said.

The EPA has prepared rules for existing plants to minimize pollution from particulate matter, mercury and other toxins. But this would be the first time the agency regulates existing plants to curb emissions of the greenhouse gases scientists believe contribute to global warming.