NEW YORK (MarketWatch) -- Sen. Joe Manchin, a Democrat from West Virginia, on Wednesday called on federal regulators to ban bitcoin, saying the unregulated virtual currency has allowed users to take part in illegal activities and is disruptive to the U.S. economy. "There is no doubt average American consumers stand to lose by transacting in bitcoin," Manchin said in a letter to regulators. "Before the U.S. gets too far behind the curve on this important topic, I urge the regulators to work together, act quickly, and prohibit this dangerous currency from harming hard-working Americans."