The average price for a gallon of gas has gone up by more than 41 cents in the past five months. Supply and demand? Hardly. The price hikes come at a time when U.S. oil inventories reached a three-decade high while demand for gasoline is lower than four years ago when prices averaged only $2.30 a gallon. So Bernie is pushing for an investigation into oil price manipulation like one already underway in Europe. He also would set a 30-day deadline for federal regulators to use emergency powers to curb excessive speculation in crude oil markets. Both ideas were offered as amendments to a bill now before the full Senate.