Turkish police on Tuesday carried out sweeping early-morning arrests in the opposition bastion of Izmir, detaining more than 120 individuals just hours before a major rally was set to take place in Istanbul.

The crackdown, tied to a corruption investigation at Izmir City Hall, comes amid intensifying pressure on the opposition Republican People’s Party (CHP) and is widely seen as the latest move in a broader campaign against President Recep Tayyip Erdogan’s critics.

Among those taken into custody were a former mayor and several senior officials, according to CHP deputy chair Murat Bakan.

Local media reported that prosecutors had issued arrest warrants for 157 people in total.

The operation bears strong resemblance to a similar sweep in Istanbul earlier this year, which culminated in the controversial removal of the city’s mayor, Ekrem Imamoglu Erdogan’s most prominent political rival and the CHP’s presumptive candidate for the 2028 presidential election.

Bakan, in a post on X, said the arrested included former Izmir mayor Tunc Soyer and the party’s provincial chairman, Senol Aslanoglu.

He slammed the arrests as politically driven rather than legally necessary.

“These are people constantly in the public eye. If summoned, they would have cooperated with authorities,” he stated, adding that many of those targeted were already under investigation. “This is a political decision, not a legal one.”

The timing of the operation raised eyebrows, coming just hours before the CHP was set to stage a rally outside Istanbul City Hall at 5:30 p.m. GMT.

The event marks 100 days since Imamoglu’s ouster and is part of a string of public demonstrations the party has organized in response to what it calls the “March 19 coup” a reference to his removal from office.

CHP leader Ozgur Ozel, also writing on X, urged party supporters to stand firm in the face of increasing pressure.

“Throughout history, there have always been those who sought to oppress but resistance has always prevailed,” Ozel wrote, without directly naming the Izmir arrests.

The Istanbul protests sparked by Imamoglu’s arrest earlier this year triggered the largest wave of civil unrest in Turkey in over a decade, with nearly 2,000 demonstrators reportedly detained during the government’s crackdown.

Though the street demonstrations have since waned, the CHP has kept up momentum through a series of nationwide rallies, boosting its popularity in recent polls.

The developments in Izmir came just a day after a court in Ankara began hearing a case alleging vote-buying during the CHP’s 2023 leadership contest.

The case could potentially annul Ozel’s election as party leader a move his supporters decry as yet another effort to weaken the opposition following the targeting of Imamoglu.

“No plot against our party is disconnected from the March 19 coup,” Ozel warned in another social media post.

Monday’s court session was brief, with the judge postponing proceedings to September 8 due to jurisdictional issues.

Meanwhile, the crackdown in Izmir unfolded as emergency services battled several large wildfires near the Aegean resort city, prompting the evacuation of more than 45,000 residents.