The primary opposition party in Turkey has claimed significant victories in the major cities of Istanbul and Ankara. These results deal a notable setback to Recep Tayyip Erdogan, who aimed to regain control of these cities less than a year after securing a third term as president.

Erdogan, who spearheaded the campaign in Istanbul, his hometown where he previously served as mayor, faced defeat as Ekrem Imamoglu, representing the secular opposition CHP, clinched his second victory.

Despite Erdogan's aspirations for a new era in Istanbul, Imamoglu secured over 50% of the vote, triumphing over the president's AK Party candidate by more than 11 points and nearly one million votes. This election marks the first nationwide defeat for Erdogan's party since he assumed power 21 years ago.

In the capital city of Ankara, opposition mayor Mansur Yavas claimed a commanding lead of 60% over his opponent, prompting him to declare victory with less than half of the votes counted.

Supporters celebrated by blocking main roads in the city, expressing jubilation with flags and car horns.

Notably, the CHP, or the Republican People's Party, also gained control of Bursa and Balikesir, Turkey's fourth-largest city, in the northwest, while maintaining control over Izmir, Adana, and Antalya.

President Erdogan, 70, acknowledged that the election did not unfold as he had hoped but emphasized to supporters in Ankara that it signifies a "turning point" rather than an end for his party.

He pledged that his party would learn from the defeat and reiterated his commitment to respecting the will of the electorate, a principle he has consistently emphasized throughout his tenure.

Despite Erdogan's consolidation of sweeping powers under his presidency, including the abolition of the prime minister position, directly elected mayors in cities still wield significant influence.

Throughout the campaign, Erdogan hinted that this would be his final term as president, given that his current term expires in 2028.

However, critics speculated that a victory in this election might have emboldened him to pursue constitutional amendments enabling him to seek re-election. Following this resounding defeat, such plans seem increasingly improbable.

Political scientist Berk Esen said the opposition CHP had delivered the "biggest election defeat of Erdogan's career" and come up with its best results since 1977.

The outcome was a big success for the chairman of the CHP, Ozgur Ozel, who praised voters for deciding to change the face of Turkey in a historic vote: "They want to open the door to a new political climate in our country."

Crowds in Istanbul gathered outside the town hall in Sarachane, one of Istanbul's oldest districts.

They waved Turkish flags and banners showing Ekrem Imamoglu's picture alongside Turkey's founding father Kemal Ataturk, whose poster was draped down the walls of the local authority building.

"I can say that our citizens' trust and faith in us has been rewarded," said Mr Imamoglu.

Both he and Mansur Yavas are seen as potential candidates to run for the presidency in 2028.

"Everything will be fine," Imamoglu supporters chanted as they danced to drums and clarinets in Sarachane, one of Istanbul's oldest districts.

Istanbul's incumbent mayor had first used the slogan when he won the city from Mr Erdogan's party five years ago. Some of the banners in Sarachane used his current slogan, "Full speed ahead".

"They're only local elections but the opposition's victory in big cities is a significant show of force against the ruling party," Imamoglu supporter Yesim Albayrak, 25, told the BBC.

Mehmet Bankaci, 27, told the BBC there was a need for change in Turkey: "If Imamoglu or Mansur Yavas had been the CHP candidate in last year's presidential election, they definitely would have won."

Istanbul hosts a fifth of Turkey's population of nearly 85 million people. Control the city and you control a significant portion of Turkey's economy including trade, tourism and finance.

Five years ago, Mr Imamoglu overturned years of AK Party rule in Istanbul with the backing of other opposition parties. But that opposition unity fell apart in the wake of last year's presidential election defeat and the AK Party had high hopes of overturning his 2019 victory.

Ahead of Sunday's election, the vote had been seen as too close to call, with a strong challenge from AK Party candidate Murat Kurum.

But the ruling party has been unable to shake off an economic crisis that has seen inflation rates of 67% and interest rates at 50%.

While broad swathes of the west, south and north of Turkey are now under the control of the opposition CHP, the pro-Kurdish Dem party has won control of much of the south-east.

Mr Erdogan's AK Party continues to dominate central Turkey and had more success in areas of the south-east devastated by the February 2023 double earthquake, including the cities of Kahramanmaras and Gaziantep.

Speaking from the balcony of his party headquarters in Ankara, he promised to use the four years before the next presidential election to "renew ourselves and compensate for our mistakes".

His supporters chanted back: "Stand still, this nation is with you."

About 61 million Turks were eligible to take part in Sunday's election and more than a million young voters were casting their ballots for the first time. Turnout was estimated at more than 77% across the country's 81 provinces.

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