U.S. Trade Representative (USTR) Robert Lighthizer speaks at an event hosted by the U.S. Chamber of Commerce in Washington D.C., the United States, on May 1, 2018. Lighthizer said on Tuesday that he hoped to reach a deal to overhaul the North American Free Trade Agreement (NAFTA) in mid-May, which could buy more time for the current Congress to approve the deal. (Xinhua/Yang Chenglin)