Thousands of protesters marched across Turkey this week after Istanbul Mayor Ekrem Imamoglu, a political rising star and major rival to President Recep Tayyip Erdogan, was sentenced to two and a half years in prison and banned from participating in politics.

Imamoglu, who has not been arrested or jailed yet, was convicted for defaming public officials. Specifically, he denounced members of Turkey’s highest election council as “fools” in 2019 because they annulled his first victory in that year’s election for mayor of Istanbul – Turkey’s largest city and its vital economic hub. 

Erdogan’s ruling AKP Party refused to recognize his victory and demanded a rerun, which Imamoglu proceeded to win again, by an even larger margin.

The 52-year-old Imamoglu is a businessman who belongs to the opposition Republican People’s Party (CHP). His victory in the Istanbul mayoral race was a major shock to the Turkish political system, especially after he increased the size of his victory during the rerun election. His supporters and allies see his conviction on charges of “insulting” government officials as a transparent effort to force a major Erdogan rival out of politics.

At protests across Turkey that began after Imamoglu’s conviction on Wednesday, his supporters hoisted photos of Mustafa Kemal Ataturk, the legendary godfather of secular Turkey whose achievements have been systematically undermined by the authoritarian Islamist Erdogan.

Imamoglu’s supporters also delighted in taunting Erdogan with his own defiant words after he was convicted of inciting religious hatred, removed as mayor of Istanbul, and imprisoned for several months in 1998. 

Erdogan got in trouble for reciting a poem that included the line, “The mosques are our barracks, the domes are our helmets, the minarets are our swords, and the faithful are our army.” After eight years of Erdogan’s rule, Turkey is no longer the sort of place where a politician would be prosecuted for talking about using mosques as barracks.

The Imamoglu contingent loves to highlight the similarities between the career paths of their man and Erdogan, who looks exceptionally vulnerable in next year’s elections. Imamoglu has not formally declared his candidacy, but he is almost always included in pre-election polling, and he usually scores higher than other plausible opposition candidates.

Imamoglu dismissed his conviction on Wednesday and asked for his supporters to rally in his defense, which they enthusiastically did. 

“I am absolutely not afraid of their illegitimate verdict. I don’t have judges to protect me, but I have 16 million Istanbulites and our nation behind me,” he told a crowd of supporters.

“Sometimes in our country, no success goes unpunished. I see this meaningless and illegal punishment imposed on me as a reward for my success,” he said.

International leaders and human rights groups denounced Imamoglu’s prosecution as a nakedly political action by Erdogan and his party. The U.S. State Department said on Thursday it was “deeply troubled and disappointed” by the judgment against Imamoglu, which is pending appeal.

“His conviction is inconsistent with respect for human rights, fundamental freedoms, and the rule of law.  We remain gravely concerned by the continued judicial harassment of civil society, media, political and business leaders in Turkey,” said State Department spokesman Ned Price.

“We urge the government to cease prosecutions under criminal ‘insult’ laws, and to respect the rights and freedoms of all Turkish citizens, including by ensuring an open environment for public debate,” Price said.

European leaders on Wednesday denounced Immamoglu’s conviction as a “heavy blow to democracy” and a “slide away from the rule of law.” 

Human Rights Watch (HRW) noted the prosecution of Imamoglu was even more absurd because the mayor of Istanbul was himself called a “fool” first, by Erdogan’s hot-tempered Interior Minister Suleyman Soylu. 

Soylu, incensed because Imamoglu criticized Turkey at an event held by the Council of Europe, snarled in November 2019: “To the fool who went there and complained about Turkey; The people will make you pay for this.”

Imamoglu said he was throwing Soylu’s own words back at him and was referring to AKP officials who refused to recognize his electoral victory in Istanbul as fools, not the Turkish electoral commission. 

“The use of the word ‘fool’ by the Interior Minister against myself is what lies at the root of the problem. This ‘fool’ remark uttered by me has been used in response to the ‘fool’ remark used against me and its addressee is the Interior Minister,” Imamoglu argued during court hearings.

“The verdict against Ekrem İmamoğlu is a travesty of justice and an attack on the democratic process, demonstrating that as the 2023 elections approach the government is prepared to misuse courts to sideline or silence key opposition figures,” said HRW deputy program director Tom Porteous.

“The verdict violates not only İmamoğlu’s rights but also denies Istanbul’s voters their rights when it deprives them of their chosen representative,” Porteous said.