For a few months this summer, the oil market speculator ... helped push oil prices steadily higher, shattering records that had lasted for decades. As oil topped $145 per barrel, Congress started looking for ways to rein the speculators in. Then oil prices plunged, and interest in the issue fizzled. But that may soon change. This will remain an issue," said Sen. Byron Dorgan, D-N.D., who introduced oil market legislation this year. "Because when the price of oil has gone from $50 to $147 and back, it's clear to me and everyone else that this has nothing to do with supply and demand. It has to do with speculation." Among possible changes, Congress may try to assert more authority over unregulated oil swaps that don't take place on any formal market. Many factors helped shove prices higher, including the growth of China's economy and the decline of the American dollar. But oil kept rising even as gasoline sales fell in the United States, the world's largest oil consumer. That wouldn't have happened if supply and demand really were driving the market, many analysts say. "The entire move from $70 (per barrel) to $147 was people fleeing the dollar and looking at oil as an asset class," said Amy Myers Jaffe, an energy research fellow at Rice University's Baker Institute. "It was speculators, so when they exited the market, we went right back to $70." Speculators are investors who trade in oil or other commodities strictly as a financial investment. They include hedge funds and investment banks as well as retirement funds.