Donald Trump is expected to withdraw the US from the Paris climate accord, according to a White House official.
But the official said there may be "caveats in the language" the president uses to announce the withdrawal, leaving open the possibility that the decision is not final.
Nearly 200 nations, including the US, agreed in 2015 to voluntarily reduce their greenhouse gas emissions in an effort to combat climate change.
During Mr Trump’s overseas trip last week, European leaders pressed him to keep the US in the landmark agreement.
He had promised during his presidential campaign to pull the US out of the deal.