Turkish President Recep Tayyip Erdogan’s party is asking for a recount of votes in Istanbul after the ruling party lost last week’s mayoral election.

In a humiliating setback for Erdogan, the opposition Republican People’s Party (CHP) narrowly won Istanbul, the country’s economic and cultural center. It also won the mayoral contest in Ankara, the capital.

A recount in some districts in Ankara is already under way, and the ruling Justice and Development Party (AKP) has asked for a full recount in Istanbul.

AKP officials say the voting in Istanbul was “tainted” and cited “organized abuse, something going beyond simple individual error.”

As of Sunday, the CHP candidate, Ekrem Imamoglu, held a slim 16,000-vote lead over the AKP in Istanbul and urged the AKP to concede.

“I understand that it is not easy to lose Istanbul after ruling it for 25 years, but this is what democracy is about,” Imamoglu said, adding that losing “is not the end of the world.”

An AKP spokesman dismissed his statement and called appealing the results a “natural.”

Erdogan was elected mayor of Istanbul in 1994, propelling him from obscurity to international headlines. Analysts say the city usually is a harbinger for what happens on Turkey’s national political stage. Losing his home city would be seen as a major setback for Erdogan and the AKP.