Back-to-back bribery scandals involving utility giants in Ohio and Illinois over the past week have given a black eye to efforts to prop up struggling U.S. nuclear plants.

On Tuesday, federal officials arrested the speaker of the Ohio House of Representatives on racketeering charges tied to a bailout of two nuclear plants owned by Energy Harbor Corp., a former FirstEnergy Corp. subsidiary. Four days earlier, Exelon Corp.’s Commonwealth Edison unit agreed to pay $200 million to resolve a lobbying probe in Illinois, where nuclear plants also receive aid.

The fallout in Ohio has been swift, with Democratic and Republican lawmakers calling Wednesday for the nuclear bailout law to be repealed immediately. Shares of FirstEnergy, which received a subpoena related to the investigation, plunged the most on record, 21 percent. Taken together, the two scandals could undermine future efforts by utilities to seek support from lawmakers.