Charles Grassley, the top Republican on the Judiciary Committee, and John Thune, a senior Republican member of the Finance and Commerce committees, asked Energy Secretary Steven Chu whether it was wise to grant financing to Fisker, which ran into production problems after receiving part of the loan.
"Though the Department of Energy has now frozen the remaining portion of Fisker's loan, questions remain as to why a loan was extended to this now 'troubled' auto company in the first place," the two lawmakers said in an April 20 letter that was released on Monday.
The Department of Energy is working with an outside consultant, Houlihan Lokey, to evaluate a variety of agency loans, including Fisker.
Fisker was approved for the $529 million loan in 2009 under a DOE program aimed at helping automakers make more fuel-efficient cars and trucks.
Fisker received about a third of the money initially to mainly support U.S. engineering and other efforts to roll out its first electric car, the $100,000 Karma, that was assembled in Finland. But delays in getting that car to showrooms prompted the DOE to hold additional financing.
Remaining funds were to go to develop a $50,000 sedan, called the Atlantic, at a former General Motors factory in Wilmington, Del. Work on the Atlantic was suspended in February.
Since the collapse of solar-panel maker Solyndra last year, congressional Republicans primarily in the U.S. House of Representatives have pressured the DOE to justify billions in loan programs aimed at green economy projects and related jobs.