Recep Tayyip Erdogan, after delivering a rousing “balcony speech” to thousands of jubilant followers overnight, is now almost certain to run for president this year or seek a fourth term as prime minister, they said.

Needled by months of corruption claims spread via Twitter and YouTube, Erdogan has vowed to go after hidden enemies in the police, justice and media whom he blames for the online leaks and pursue them “in their lairs”.

“Emerging strongly from the elections, Erdogan will likely run for president during the summer,” said Soner Cagaptay of the Washington Institute think-tank. With memories fresh of last June’s violence — when eight people died, thousands were injured and clouds of tear gas wafted through Istanbul’s Gezi Park — many feared further dangerous tensions ahead.

“The government says it will launch a witch-hunt against the media (and) civil society,” said the head of the secular opposition Republican People’s Party (CHP), Kemal Kilicdaroglu.

“We will monitor this carefully. We will stand by our people if their rights are violated.” Cagaptay predicted that “Erdogan will become more authoritarian. Turkey will be polarised further, with unrest and demonstrations. The government will crack down on the opposition further, with the potential of a deadlock and regime crisis.”

Even though Sunday’s nationwide polls were for city mayors and municipal officials, they were seen by all sides as a crucial popularity test for Erdogan and his Islamic-rooted Justice and Development Party (AKP).

Nationwide, the AKP garnered 45 per cent of the vote compared with 28 per cent for the CHP; scored a crushing victory in mega city Istanbul; and claimed a narrow win in the capital Ankara. Turkey has now become “Tayyip-Land”, said the critical Taraf daily. “Going forward Erdogan will see himself as invincible, and as deeply wronged by his rivals,” said Brent Sasley of Texas University.

“He might feel safe now, and so relax his grip a little on Turkish media. More likely he will seek revenge against those who, in his view, tried to take him down but failed.” Erdogan has earned rebukes from Nato partners for heavy handed police action against Gezi protesters, and for blocking Twitter and YouTube to stop a torrent of corruption claims against his allies and relatives.

A European Commission spokesman said on Monday that EU candidate Turkey “now urgently needs to re-engage fully in reforms in line with European standards on rule of law and fundamental rights”. Amid Turkey’s bitter standoff, Erdogan has accused Fethullah Gulen, an influential US-based Muslim cleric, and his loyalists of being behind the leaks that went viral on social media. Despite the turmoil, millions of Turkish voters shrugged of such concerns and preferred to take their chances with the man often dubbed “the sultan”, whose 11-year rule has driven strong economic growth. “In the end nothing was able to dent Erdogan’s allure,” Sasley told AFP.

“It seems that the Turkish public was simply not ready to take a chance on an uncertain future.”

The vote result exposed deepening faultlines in Turkey, between a secular and globally connected urban middle class and the vast country’s conservative Muslim heartland.

Turkey’s first mayor wearing a Muslim headscarf — long banned for civil servants under previous secular governments — won office in a district of the central AKP stronghold of Konya.

Meanwhile Twitter user Gizemm56, defying the ban, wrote: “My biggest concern is, this man shut down Twitter before the elections, I cannot imagine what’s going to happen after the elections.”

Finansbank economist Deniz Cicek noted that, while post-election “balcony speeches” are usually conciliatory, Erdogan’s midnight address “was peppered with references to treason and traitors”. “The tone of the speech suggests that Erdogan is unlikely to back down from his confrontational stance and a highly charged political environment is set to continue until the presidential elections in August,” Cicek said.