Generation of electricity is the second largest source of carbon dioxide and other planet-warming gases in the United States.

The Trump administration plans to announce Monday that the United States will no longer limit the planet-warming pollution that power plants pump into the air while burning coal and gas, according to two people familiar with the proposal.

The shift by the Environmental Protection Agency would complete the administration’s erasure of the most consequential climate policies of Presidents Joseph R. Biden Jr. and Barack Obama. If the move survives expected legal challenges, it could also prevent future administrations from regulating greenhouse gas emissions from power plants.

The power sector is the second largest source of carbon dioxide and other greenhouse gases in the United States. This pollution accumulates in the atmosphere, where it traps the sun’s heat, raising temperatures and supercharging extreme weather events around the globe. Scientists say the United States and other industrialized nations must sharply cut emissions to avoid the most devastating impacts of climate change.

Lee Zeldin, the E.P.A. administrator, is expected to announce the change during a meeting of energy ministers from the Group of 20 nations in Houston, according to the two people familiar with the matter, who requested anonymity to describe the proposal before it is made public.

Representatives for the E.P.A. did not immediately respond to a request for comment late Sunday evening.

Environmentalists and energy experts have opposed the move, which has been in the works since last spring. They have noted that if the U.S. power sector were its own country, it would be the fifth-largest climate polluter in the world after China, the entire United States, India and Russia.