ISTANBUL — Ekrem Imamoglu, whose tenure as Istanbul mayor was cut short after an extraordinary decision to nullify his electoral victory, kicked off his rerun campaign this week, vowing to retake control of the municipality and end the profligacy he said he unearthed during his 18-day stint in office.

But in a sign of the pressure Imamoglu’s campaign faces, a prosecutor has prepared a criminal indictment against his chief strategist for allegedly inciting enmity and spreading “terrorist” propaganda on social media, according to the opposition Republican People’s Party (CHP).

Imamoglu told a room packed with hundreds of supporters on Wednesday that he would fight anew in the June 23 election to restore faith in the ballot box, despite the “great injustice” of having his mandate revoked when electoral officials ordered that votes be recast after the ruling Justice and Development Party (AKP) petitioned for the election's cancellation.

“No one should lose their hope in democracy or the ballot box,” Imamoglu told the crowd. “To protect the principles of democracy and the honor of the ballot box, we will show everyone that there is no alternative to democracy and the vote.”