LYON (euronews) — Turkish President Tayyip Erdogan has suffered a heavy blow after his ruling AK Party lost control of the capital Ankara for the first time in nearly two decades in a local election as an opposition party also claimed victory in Istanbul.

Turkish media said the opposition Republican People’s Party (CHP) candidate Mansur Yavas had won a clear victory in Ankara but there was a tense standoff in Istanbul as both the opposition and the AK Party claimed victory in the polls due to a narrow margin.

The AK Party said former Prime Minister Binali Yildirim defeated his CHP rival Ekrem Imamoglu by just 4,000 votes in Istanbul, while Imamoglu said he had a lead of 28,000 with only 2,000 votes uncounted.