ISTANBUL (AP) — Voters in Turkey have begun casting ballots in municipal elections that are seen as a barometer of President Recep Tayyip Erdogan's popularity amid a sharp economic downturn in the nation that straddles Europe and Asia.

More than 57 million voters are eligible to choose mayors, local representatives and neighborhood or village administrators. The elections are being held as Turkey faces an economic recession, rising food prices and high unemployment.

Erdogan's past electoral successes have been based on economic prosperity, but opinion polls suggest this time around his ruling party could lose control of Turkey's large cities, including Ankara, the capital.

Erdogan has campaigned heavily for his party's candidates, declaring Turkey's economic woes "an attack" on the country and framing the elections on Sunday as matter of "national survival."