WASHINGTON — New efforts by President Trump and his staff to question or undermine the established science of climate change have created a widening rift between the White House on one side, and scientific facts, government agencies, and some leading figures in the president’s own party on the other.

The president’s senior advisers are exploring the idea of creating a panel aimed at questioning the National Climate Assessment. According to a White House memo, the group would include William Happer, a Princeton physicist who has asserted that carbon dioxide — a greenhouse gas that scientists say is trapping heat and warming the planet — is beneficial to humanity.

The climate assessment, a sweeping report issued by the White House itself in November, concluded decisively that the burning of fossil fuels was warming the atmosphere, leading to a raft of harmful effects across the United States and the world.

And Mr. Trump announced last week on Twitter that he would nominate Kelly Knight Craft to be his ambassador to the United Nations. Ms. Craft said in a 2017 television interview that, on the issue of climate change, she believes there are “scientists on both sides that are accurate.”

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