Turkish prosecutors are seeking a prison sentence for the mayor of Istanbul, seen as a possible challenger to long-time President Tayyip Erdogan, for insulting election authorities, state-owned news agency Anadolu reported on Friday. Ekrem Imamoglu, from the main opposition Republican People's Party, was elected mayor of Turkey's biggest city in June 2019 in a re-run vote after an earlier election was cancelled over allegations by Erdogan's ruling AK Party of fraud. The prosecutors' indictment calls for a 4-year sentence against Imamoglu for insulting Supreme Election Boa...