WASHINGTON — As the government struggles to keep businesses afloat through the pandemic, the Trump administration is sitting on about $43 billion in low-interest loans for clean energy projects, and critics are accusing the Energy Department of partisan opposition to disbursing the funds.

Congress is already considering more coronavirus relief, despite a growing concern for an annual budget deficit projected to near a staggering $4 trillion. To some energy experts and lawmakers, it is unconscionable that tens of billions of dollars that Congress long ago authorized has sat unused.

“We’re searching high and low all over Washington, D.C., for money to put people back to work and here we have more than $40 billion,” said Dan Reicher, executive director of the Steyer-Taylor Center for Energy Policy and Finance at Stanford University, who served at the Energy Department under President Bill Clinton. “This is the moment to really put these programs back in gear.”

The loans — which would aid renewable power, nuclear energy and carbon capture and storage technology — had some bipartisan support even before the coronavirus pushed 30 million people onto the unemployment rolls. But some supporters of the program said it was being held back by a president who has falsely claimed wind power causes cancer and consistently sought deep cuts to renewable energy spending, including the loan program.