The most powerful part of U.S. President Joe Biden’s climate agenda — a program to rapidly replace the nation’s coal— and gas-fired power plants with wind, solar and nuclear energy — will likely be dropped from the massive budget bill pending in Congress, according to congressional staffers and lobbyists familiar with the matter.

Sen. Joe Manchin, the Democrat from coal-rich West Virginia whose vote is crucial to passage of the bill, has told the White House that he strongly opposes the clean electricity program, according to three of those people. As a result, White House staffers are now rewriting the legislation without that climate provision and are trying to cobble together a mix of other policies that could also cut emissions.

A spokesperson for the Biden administration declined to comment, and a spokesperson for Manchin did not respond to an emailed request for comment.