LEON, Nicaragua (Reuters) - After years of setbacks, many Nicaraguans from Leon, the cradle of the 1979 Sandinista revolution, believe their aging former guerrilla leaders could soon return to power in elections that could also prove a diplomatic nightmare for Washington. "We need a change. It's been bad, bad, bad," said 60-year-old war Sandinista war veteran Daniel Sauro, referring to 16 years of pro-Washington governments that took power after Sandinista leader Daniel Ortega's electoral defeat in 1990. Sauro lives in a city where colonial churches and dilapidated houses are still splattered with aging bullet holes from 1970s street battles between...