Ekrem Imamoglu, the mayor of Istanbul and a popular figure, had boasted jokingly that he was the only person to have beaten Recep Tayyip Erdogan’s ruling party in three local elections.

Umit Bektas/Reuters Supported by By Ben Hubbard Reporting from Istanbul Turkey has been plunged into a political crisis after the authorities arrested Ekrem Imamoglu, the mayor of Istanbul and the ...