Senate Energy and Natural Resources Committee chairman Jeff Bingaman (D.-N.M.) sent a letter to the Commodity Futures Trading Commission (CFTC) this week asking the agency to “dig more deeply” as it investigates the role of speculation and non-commercial, institutional investors in raising the price of oil to today’s levels. Senator Bingaman also questioned the “adequacy” of CFTC’s regulatory oversight. The letter comes as lawmakers face continued pressure to soften the impact of fuel prices for American families and businesses.

Bingaman’s biggest concerns, according to the press release explaining the letter:

the CFTC does not collect data on or analyze the fastest growing segment of energy commodity trading, lumps speculators together with more traditional energy market participants in its analyses, and has much lower transparency requirements for energy compared to agricultural commodities.

Bingaman says he understands that “tight oil market fundamentals and geopolitics” are playing a key role in determining oil prices — but recent analysts’ testimony suggesting supply and demand for physical barrels of oil simply cannot fully explain prevailing oil prices has Bingaman looking for other answers, specifically “the impacts of speculative investment” on prices.

A main concern for Bingaman and others critical of the energy trading platform is that more and more trading activity for crude oil is taking place on foreign boards of trade and in over-the-counter markets. Here the CFTC has limited oversight.