Turkish police have arrested Istanbul Mayor Ekrem İmamoğlu on what his supporters say are trumped-up corruption charges ahead of primary elections scheduled for Sunday. İmamoğlu is a major challenger to Turkey’s authoritarian President Recep Tayyip Erdoğan. In 2022, he was found guilty of insulting public officials and sentenced to prison, but has remained free pending an appeal. Turkish police also arrested 100 other people, including one of İmamoğlu’s close aides. Authorities have also closed roads around Istanbul and banned protests in the city for four days, while restricting access to social media sites.