WASHINGTON, May 23 (Reuters) – The U.S. Senate's top Democrat said on Tuesday he and President Joe Biden's administration were engaging allies and businesses to address China's ban on sales of memory chips made by U.S.-based Micron Technology Inc (MU.O). The restrictions this week by China's cyberspace regulator against Micron, the biggest U.S. memory chipmaker, were the latest in a widening trade dispute between the world's two largest economies. "The Chinese government's announced action against Micron is not based in fact and is a troubling use of economic coercion against the U.S.," Senate Majority Leader Chuck Schumer said. "I am…