ISTANBUL — A court in Turkey barred the mayor of Istanbul from political activity for years after convicting him on charges of insulting public officials, a ruling that could sideline a rising star in the opposition who is seen as a potential challenger to President Recep Tayyip Erdogan in elections next year.
The mayor, Ekrem Imamoglu, runs Turkey’s largest city and economic center. He was sentenced to two years and seven months in prison but has not been arrested and will appeal the ruling, his party said. If the ruling stands, he would not go to prison because his sentence is below the threshold required for incarceration under Turkish law.
But he would be removed as mayor and barred for the duration of his sentence from political activity, including voting, being a member of a political party and running for or holding public office. That could essentially destroy the near-term prospects of a leader with a proven record of winning elections against Mr. Erdogan’s ruling Justice and Development Party, or A.K.P.
Mr. Imamoglu was charged with insulting public officials, a crime under Turkish law. But his supporters see the case against him as a ruse cooked up by Mr. Erdogan and his allies to remove a contender from the political scene.
“A couple of people cannot take away that easily the authority that the people gave,” Mr. Imamoglu said after the verdict was announced, speaking in a video posted on Twitter. “Our struggle becomes stronger.”
Turks are looking to parliamentary and presidential elections to be held in or before next June to determine the future course of this country of 85 million, one of the world’s 20 largest economies and a member of NATO.
Mr. Erdogan, as the country’s predominant politician for nearly two decades and president since 2014, has pushed Turkey toward greater authoritarianism, using his influence over broad swaths of the state to bolster his rule and undermine his rivals. He will seek to extend his tenure next year, although his standing in the polls has dived because of an economic crisis. The Turkish lira has lost much of its value against the dollar, and year-on-year inflation is more than 80 percent, according to government figures.
A coalition of six opposition parties hopes to unseat Mr. Erdogan and deprive his party of its parliamentary majority next year, but they have yet to announce a presidential candidate.
Mr. Imamoglu has not spoken publicly about whether he will run for president, but some recent polls have found him to be more popular than Mr. Erdogan. He also has the rare distinction of having beaten Mr. Erdogan’s party for control of Turkey’s largest city, twice in the same year.
In March 2019, Mr. Imamoglu beat Mr. Erdogan’s chosen candidate in Istanbul’s municipal election, putting Turkey’s largest opposition party in charge of the city for the first time in more than three decades. It was a stinging loss for Mr. Erdogan, not least because he had grown up in the city and made his own political name as its mayor before moving on to national politics.
Alleging electoral irregularities, Mr. Erdogan’s party appealed for and were granted a rerun. Mr. Imamoglu won that too, with an even larger margin than he had the first time around.
The current case against Mr. Imamoglu has its roots in his public criticism of government decisions in 2019 to remove dozens of mayors from Turkey’s Kurdish minority from their posts and replace them with state-appointed trustees.
The government accused those mayors of having ties to the Kurdistan Workers’ Party, a Kurdish militant group that has fought against the state and which Turkey, the United States and the European Union consider a terrorist organization. The mayors denied the charges and critics considered their ouster a subversion of the democratic process.
In a speech, Turkey’s interior minister, Suleyman Soylu, called Mr. Imamoglu a “fool” for criticizing the mayors’ removal. Mr. Imamoglu responded that the “fool” was those who had annulled the original results of the Istanbul mayoral elections.
Turkey’s Supreme Election Council, which oversees the country’s elections, filed a compliant against Mr. Imamoglu for insulting state officials. A state prosecutor formally charged Mr. Imamoglu last year.
Critics have accused Mr. Erdogan of extending his influence over the judiciary, allowing him press for rulings that benefit him politically.
In a video message posted on Twitter before the sentence was announced on Wednesday, Kemal Kilicdaroglu, the head of Turkey’s largest opposition party, said that a guilty verdict would prove that Turkey’s judges were in cahoots with Mr. Erdogan.
“Any decision other than an acquittal will be the confession of a plot and the palace’s orders,” he said, referring to the presidential palace. “I am warning the palace for the last time, get your hand off the judiciary.”