U.S. Sen. Roger Wicker, R-Miss., ranking member of the Senate Committee on Commerce, Science, and Transportation, Thursday sent a letter to Lina Khan, Chair of the Federal Trade Commission, calling on the agency to provide evidence to support suggestions from the White House and Democrats in Congress that market manipulation, collusion, or other improper or illegal behavior in the gasoline and crude oil markets is responsible for the surges in gas prices in the U.S.

“It is clear that gas prices have risen due to the current administration’s zealous agenda to reduce domestic oil and gas production combined with surging inflation caused by a significant increase in government spending,” Wicker wrote. “However, some have proposed that the cause of rising gas prices is not these factors but rather market manipulation or some other type of collusion among members of the oil and gas industry. If Congress is to properly address the current crisis and provide relief to Americans in need, we must be fully informed of the potential underlying causes of skyrocketing gas prices.”

Wicker’s inquiry follows recent claims that inflated gas prices are the result of exploitation by the oil and gas industry, rather than the reduction of domestic fossil fuel production and the escalating crisis in Ukraine.

Read the letter here.