The leader of main opposition Republican People's Party (CHP) Ozgur Ozel addresses his supporters during a rally, in Ankara, Turkey, September 14, 2025, one day before a court is set to decide whether to annul the party’s last general congress and remove Ozel from leadership. REUTERS/Umit Bektas
Supporters of main opposition Republican People's Party (CHP) attend a rally, a day before a court is set to rule on whether to annul the party's last general congress and unseat its leader Ozgur Ozel, in Ankara, Turkey, September 14, 2025. REUTERS/Umit Bektas
Workers hang a banner featuring images of main opposition Republican People's Party (CHP) leader Ozgur Ozel and jailed Istanbul Mayor Ekrem Imamoglu ahead of a rally, a day before a court is set to rule on whether to annul the party's last general congress and unseat its leader, in Ankara, Turkey, September 14, 2025. REUTERS/Umit Bektas
Supporters of main opposition Republican People's Party (CHP) attend a rally, a day before a court is set to rule on whether to annul the party's last general congress and unseat its leader, in Ankara, Turkey, September 14, 2025. REUTERS/Umit Bektas

ANKARA (Reuters) -Tens of thousands of people protested in the capital Ankara on Sunday against a court case that could oust the head of the main opposition on Monday after a year-long legal crackdown on hundreds of its members.

Live footage showed crowds chanting for President Tayyip Erdogan's resignation while waving Turkish flags and party banners.

The court decision on Monday whether to invalidate the 2023 congress of the Republican People's Party (CHP) over alleged procedural irregularities could reshape the party, rattle financial markets and influence the timing of a general election set for 2028. The court could also delay the ruling.

Speaking at Sunday's rally, CHP leader Ozgur Ozel said the government was trying to cling to power by undermining democratic norms and suppressing dissent following opposition victories in local elections over the past year.

Ozel also called for a snap general election.

TURKISH OPPOSITION VOWS TO RESIST

"This case is political. The accusations are slander. Our comrades are innocent. What's being done is a coup — a coup against the future president, against the future government. We will resist, we will resist, we will resist," Ozel said in his address to the crowd.

The government says the judiciary is independent and denies any political motives.

Turkey has detained more than 500 people, including 17 mayors over the last year in Istanbul and other CHP-run municipalities around the country as part of corruption investigations, according to a Reuters review.

Hundreds of members of the CHP have been jailed pending trial in a sprawling probe into alleged corruption and terrorism links, among them President Tayyip Erdogan's main political rival - Istanbul Mayor Ekrem Imamoglu.

The arrest of Imamoglu in March sparked the country's largest protests in a decade where hundreds of thousands took to the streets, prompting a brief but sharp selloff in the lira and other Turkish assets.

In a letter sent from prison and read aloud at the rally in Ankara, Imamoglu wrote that the government is attempting to pre-determine the outcome of the next election by sidelining legitimate rivals. He also accused the government of undermining democracy through politically motivated judicial actions and other efforts to suppress dissent.

"The era of 'I' in this country will end, and the era of 'we' will begin. One person will lose, and everyone else will win," Imamoglu wrote.

The crowd applauded and chanted "President Imamoglu" after the letter read aloud.

(Reporting by Umit Bektas and Ezgi Erkoyun; editing by Philippa Fletcher)