By David Shepardson WASHINGTON (Reuters) – Two U.S. House Democrats on Tuesday proposed making it unlawful for airlines to offer flights if they know they lack sufficient staff or to cancel flights close to scheduled departures because of foreseeable staffing issues. In a summer of growing frustration over tens of thousands of canceled flights, Representatives Jan Schakowsky and David Cicilline said their proposal would give the Federal Trade Commission (FTC) and state attorneys general new powers to act. “Stronger enforcement of the airline industry is urgently needed,” said Schakowsky. “The …