Istanbul’s embattled Ekrem Imamoglu spent his first night in jail Monday a day after his suspension as mayor, as 10 journalists were detained for covering the mass demonstrations that his detention sparked across Turkey.

The protests began in Istanbul after Imamoglu’s arrest on Wednesday and have since spread to more than 55 of Turkey’s 81 provinces, sparking clashes with riot police in the country’s worst street protests in more than a decade.

Imamoglu has been widely seen as the only politician who could defeat Turkey’s longtime authoritarian leader Recep Tayyip Erdogan at the ballot box and his arrest came just days before he was to be named as the opposition candidate in the 2028 presidential elections.

In just four days, he went from being the popular mayor of Istanbul — a post that launched Erdogan’s political rise decades earlier — to being arrested, interrogated, jailed and stripped of the mayorship as a result of a graft and terror probe.

Imamoglu’s arrest and jailing drew a sharp condemnation late Sunday from France’s foreign ministry, which denounced his imprisonment as “a serious attack on democracy.”

Earlier on Sunday, some 15 million people had voted in a symbolic primary election organized by the main opposition CHP in support of Imamoglu as the party’s presidential candidate for the 2028 election.

Observers said it was the looming primary that triggered the move against Imamoglu, the main political rival of Erdogan who has dominated Turkey’s politics since 2003, first as prime minister and then as president.