A Turkish court adjourned until November the hearing of Istanbul Mayor Ekrem Imamoglu, a popular opponent of President Tayyip Erdogan, after gatherings near the courthouse were banned under heavy police watch on Wednesday, the opposition party said.

Imamoglu, whom polls suggest would be a strong possible challenger to Erdogan in national elections next year, is charged with insulting public officials in a speech he made about a re-run of the 2019 mayoral election that he won.

The case could lead to a political ban for Imamoglu if he were found guilty.

The hearing was adjourned to November 11, after having already been adjourned in June.

All main roads to the court were closed by hundreds of police officers, and hundreds more people were gathered in the district of eastern Istanbul, according to a Reuters witness.

The local governor’s office said it banned press statements and marches to protect public order, given that many people would show up to express support for Imamoglu, who swept to office in 2019 in a shock to Erdogan’s ruling AK Party.

Canan Kaftancioglu, who heads the Istanbul office of the main opposition Republican People’s Party (CHP), criticised the decision.

“What does it mean to ban entering the courthouse, following the case… Do not be afraid, we are the people, we are right and of course we will win,” she said in a tweet.