Tens of thousands of people have taken to the streets across Turkey after Ekrem Imamoglu, Istanbul’s mayor and the main rival to President Recep Tayyip Erdogan, was arrested on corruption charges. Imamoglu was set to be the Republican People’s Party’s (CHP) presidential nominee for 2028, but his arrest has sparked intense protests, the largest unrest in the country in over a decade.

Protests erupted late on Sunday, with police using water cannons, tear gas, and pepper spray to disperse crowds. Imamoglu, who was arrested on charges including bribery, extortion, and organizing a criminal group, maintains that the allegations are politically motivated. He described the arrest as a “black stain” on Turkey’s democracy and urged people to join protests.

The protests, which have spread to over 55 provinces, are among the largest in recent years, comparable to the 2013 Gezi Park protests. Imamoglu’s party says millions participated in a solidarity vote. His arrest does not stop him from running for president in 2028 unless convicted, but his political future is uncertain due to other legal challenges, including a potential revocation of his university degree.