In setback to Erdogan, Turkish opposition makes big gains in local elections

Turkey's main opposition party retained its control over key cities and made huge gains elsewhere in Sunday's local elections, preliminary results showed, in a major upset to President Recep Tayyip Erdogan, who had set his sights on retaking control of those urban areas.

With nearly 60% of the ballot boxes counted, incumbent Mayor Ekrem Imamoglu, of the Republican People's Party, or CHP, was leading in Istanbul, Turkey's largest city and economic hub, according to state broadcaster TRT. Mansur Yavas, the mayor of the capital Ankara, retained his seat with a large margin, the results indicated.

The CHP was leading in 36 of Turkey's 81 provinces, according to the results reported by TRT.

The vote was seen as a barometer of President Erdogan's popularity as he sought to win back control of key urban areas he lost to the opposition in elections five years ago. The...