A Turkish court sentenced Istanbul Mayor Ekrem Imamoglu to jail on Wednesday and imposed a political ban on the opposition politician who is seen as a strong potential challenger to President Tayyip Erdogan in elections next year.

Imamoglu was sentenced to two years and seven months in prison along with the ban, both of which must be confirmed by an appeals court, for insulting public officials in a speech he made after he won Istanbul‘s municipal election in 2019.

Imamoglu called the ruling political and unlawful, and said it was a sign of current conditions in the country.

Ahead of the verdict, a few thousand Imamoglu supporters rallied outside the municipality headquarters on the European side of the city after Imamoglu called on Twitter for them to gather. “Truth, law, justice,” they chanted.

Across the Bosphorus on the Asian side of the city of 17 million people, riot police were stationed outside the courthouse, although Imamoglu continued to work as usual, dismissing the court proceedings.

“Such a handful of people cannot take the authority given by the people. Our struggle is beginning to get even stronger, with God’s permission,” Imamoglu said in a brief video shared on a muncipality website.

The ruling comes just six months ahead of scheduled presidential and parliamentary elections, in which Imamoglu has been mooted as a possible leading challenger to Erdogan. A main opposition presidential candidate has not yet been chosen.

‘Fools’

Imamoglu, from the opposition Republican People’s Party (CHP), was tried over a speech after Istanbul elections when he said those who annulled the initial vote – in which he narrowly defeated a candidate from Erdogan’s AK Party – were “fools”.