Erdogan and Opposition Both Claim Lead in Turkish Election

ISTANBUL—Turkey’s ruling party and its opponents both claimed a lead in one of the most critical elections in the country’s history—a vote that could bring to an end the long rule of President Recep Tayyip Erdogan and have far-reaching geopolitical consequences for the Middle East, Ukraine and the North Atlantic Treaty Organization.

Neither Mr. Erdogan nor his main opponent, opposition leader Kemal Kilicdaroglu, could claim an outright victory as of early Monday local time.