AsianFin--The U.S. Senate Budget Committee on Thursday launched an investigation into domestic oil producers in regards to any collaboration with the Organization of the Petroleum Exporting Countries (OPEC) to manipulate oil prices, in the latest effort by Democratic lawmakers to pressure energy companies.

The producers the committee is probing include Exxon Mobil, Chevron, ConocoPhillips, and 14 others.

“Based on recent events involving Pioneer Natural Resources … I am concerned about the possibility that oil and gas companies could be engaging in collusive, anti-competitive activities with OPEC+ that would raise crude oil prices, resulting in higher costs not only for American families, but also for the U.S. government when it acquires crude oil for the Strategic Petroleum Reserve,” the White House said in a statement.

OPEC is an organization enabling the co-operation of leading oil-producing and oil-dependent countries in order to collectively influence the global oil market and maximize profit. The organization, which currently comprises 12 member countries, accounted for an estimated 30% of global oil production.