(CNN) -- Turkish Prime Minister Recep Tayyip Erdogan dominated debates leading up to Sunday's local elections, even though he wasn't on the ballot.
Even before results were announced, a triumphant Erdogan spoke to cheering supporters from the balcony of the headquarters of his ruling Justice and Development Party, calling the vote a victory for democracy in Turkey.
Erdogan said he delivered an "Ottoman slap" to opponents at the polls. He compared his opponents to medieval assassins, and he vowed to pursue them.
Even though Erdogan wasn't running for office, the closely watched municipal votes could show how much recent controversies and corruption probes are affecting support for him and his ruling party.
CNN sister network CNN Turk reported that Erdogan's party had taken a strong early lead in the vote count, but opposition sources contest that.
Erdogan's government faces a corruption probe, waves of street protests have wracked the country for nearly a year, and the country's once-booming economy is slowing down.
"Despite all the undesired statements at rallies, today people will tell the truth and it will be beyond everything," Erdogan told journalists as he cast his vote earlier Sunday. "People's words will be decisive rather than those who spoke at rallies. For me, people will make the final call, and we respect people's decision."
As authorities counted votes in the nationwide municipal elections Sunday, rival parties claimed victory in the races for mayor in Turkey's largest cities.
The municipal vote is seen as a test of strength for Erdogan and the ruling Justice and Development Party, which has been in power since 2002.
Erdogan, who took office in 2003, has been on the political defensive since December, when police detained dozens of people close to his government as part of a wide-ranging corruption probe. In subsequent weeks, the Prime Minister dismissed thousands of police commanders as well as the prosecutors leading the investigation.
In early March, the death of a 15-year-old boy who had been hit in the head with a tear-gas canister during a demonstration last June sparked a new round of demonstrations. An Istanbul crowd chanted "fascist government, Erdogan killer" as Berkin Elvan's coffin was carried through the streets of his family's working-class Istanbul neighborhood.
Erdogan fought back against critics who used social networks to attack him by vowing earlier this month to "eradicate" Twitter. The Twitter crackdown follows earlier threats by Erdogan to shut down Facebook and YouTube.
Anonymous critics used the popular social networking sites to publish a series of audio recordings online that appear to be wiretaps of conversations of high-level officials, including Erdogan himself. The government has accused social media platforms of being used to spread false information and lies.
The Prime Minister has called some recordings "immorally edited material," including one in which a man who sounds like him purportedly instructs his son to hide tens of millions of dollars in cash from investigators. But he has also confirmed the authenticity of other wiretaps, including one in which he is heard telling the head of a major television news network to cut short the live broadcast of a rival politician's speech in parliament.
"The electoral campaigns have been tough," Turkish President Abdullah Gul said as he voted. "But I want Turkish people to remember that our state is strong. State institutions are also strong. The problems we face will be resolved within a legal framework."
The leader of the main opposition Republican People's Party, Kemal Kilicdaroglu, told reporters Sunday that he expected a "good" outcome.
"I have always told people, 'Listen to your conscience and vote accordingly.' I hope they will do that," Kilicdaroglu said. "I am happy, I cast my vote. Democracy in Turkey should be strengthened. It should be renewed. We will build it from the start. I trust my people. I trust their judgment."
CNN's Mohammed Tawfeeq and Fionnuala Sweeney contributed to this report.