ANKARA, April 2 -- After millions of Turkish voters went to the polls on Sunday to elect local authorities in 81 provinces, the ruling Justice and Development Party, or AKP, suffered a major blow as the main opposition CHP scored victories across the country, consolidating its control in conservative strongholds with its biggest victory since 1977.

Experts suggested Sunday's vote was a barometer of the national feeling among voters who have long struggled with a severe cost of living crisis.

The main question of the mayoral election was whether incumbent Istanbul Mayor Ekrem Imamoglu, 52, an arch-rival of President Recep Tayyip Erdogan and a charismatic leader in his own right, could secure re-election in the city of 15.7 million people, ...