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.

"At a time when major refiners and oil companies are making record profits and American families continue to struggle with gasoline at record prices the idea that refiners may be manipulating the market to keep prices artificially high goes beyond reproach," the Democrats write in the letter.

Gas prices recently reached a national average above $4 per gallon.

American Petroleum Institute Chief Economist John Felmy told Politico the call for a probe was "kind of like the 'Casablanca' moment; you know, round up the usual suspects."