President is expected to speak on the signing of the landmark global climate agreement at around 2:30 p.m.
The White House is praising what it calls "the most ambitious climate change agreement in history" after the United States and nearly 200 other countries backed the deal in Paris.
President Barack Obama plans to speak about the agreement at 5:30 p.m. Eastern from the White House Cabinet Room.
The White House says the accord establishes "a long-term, durable global framework" to cut greenhouse gas emissions.
The U.S. is the world's second largest climate polluter, and Obama has pledged that the U.S. will cut its overall emissions by 26 percent to 28 percent by 2030.
The climate talks already had run into opposition from Republicans who control Congress. They say Obama's commitment to reduce emissions from U.S. power plants would cost thousands of American jobs and raise electricity costs.
"We can expect the administration to cite this `agreement' as their excuse for establishing emission targets for every sector of the U.S. economy not only including utilities, but petroleum refining, all manufacturing, agriculture and others," said Sen. James Inhofe, R-Okla., chairman of the Senate Environment and Public Works Committee.
Secretary of State John Kerry responded quickly to GOP opposition, particularly from Inhofe and candidates:
"It's already happening," Kerry said in Paris. "I have news for Senator Inhofe: the United States of America has already reduced its emissions more than any other country in the world."
Sen. Harry Reid, the Democratic minority leader, said climate change poses one of the greatest threats the world has ever known, and that no country acting alone can stem the tide.
"The time to act is now," Nevada's Reid said.