Oklahoma Attorney General Scott Pruitt is expected to testify before a congressional committee in Washington Thursday.
Pruitt is scheduled to talk about energy and environmental issues with members of a U.S. House Subcommittee on Energy and Power.
The panel is overseeing the Environmental Protection Agency's proposed new greenhouse gas rules that affect electricity generation.
Oklahoma's first-term Republican attorney general is expected to discuss his lawsuit against the EPA over that agency's rules regarding regional haze.
Pruitt contends the agency exceeded its authority when it denied Oklahoma's plan to address haze that affected visibility in state wildlife areas.
In September, Pruitt issued the following statement concerning the proposed rules:
"This is a continued erosion of the cooperative federalism that is embodied in the Clean Air Act, and further entrenches the EPA's disregard of the law's principles through unprecedented regulations," Attorney General Scott Pruitt said. "We are reviewing the announcement's potential effects on Oklahoma, but based on the EPA's interpretation of the law, it could affect all energy sources, leaving Oklahoma consumers holding the bill."
Oklahoma utility officials have said the new haze requirements are expected to lead to higher electric rates because of the investment that will be needed for coal-fired plants.
The Associated Press contributed to this report.