Democratic leaders in the Senate have sent a letter to the Federal Trade Commission requesting a probe into gas price fixing.

"Recent reports have indicated that U.S. refiners are cutting back on U.S. gasoline stockpiles in order to artificially keep prices high and inflate their bottom line," part of the letter reads. "If true, this behavior is a direct affront to the American people who are still struggling with the economic downturn."

Sen. Claire McCaskill (D-Missouri) is spearheading this push against oil companies, and the letter is also signed by Senate Majority Leader Harry Reid (D-Nevada), Sen. Charles Schumer (D-NY), Sen. Patty Murray (D-Washington) and Sen. Dick Durbin (D-Ill.).

The letter cites data from the Energy Information Administration, showing that U.S. refineries are currently only working at 81.7 percent capacity, whereas at the same time last year, they were working at closer to 88 percent capacity.