Venezuela opposition challenges Maduro with unofficial referendum

By Diego Oré and Eyanir ChineaCARACAS (Reuters) - President Nicolas Maduro's foes announced plans on Monday for an unofficial referendum to let Venezuelans have their say on his plan to rewrite the constitution and the opposition's alternative push for an election to replace him.The opposition, starting a fourth month of street protests against the socialist government it decries as a dictatorship, will organize the symbolic vote for July 16 as part of its strategy to delegitimize the unp