Ousmane Sonko is due in court on Thursday for a hearing in a libel case brought by the tourism minister, who alleged that Sonko had accused him of embezzlement without proof.
Sonko's supporters have taken to the streets several times in past weeks to denounce a trial they say is an attempt by President Macky Sall's government to weaken his opponents ahead of the polls. The government denies this.
If found guilty, Sonko, 48, who came third in the 2019 presidential election and has declared he will run in the February 2024 election, could be struck from the voter roll and disqualified as a candidate.
Violence erupted on the day of Sonko's last court appearance on March 16, as police fired tear gas at supporters accompanying his motorcade to the courthouse. Demonstrators burned tires and set fire to buses and a supermarket.
Sonko has called for more nationwide protests, while in response, authorities have banned demonstrations in the capital Dakar and deployed security forces to block off the meeting point in front of the main university campus.
The charismatic former tax inspector, who has won support among Senegal's disenfranchised urban youth, has become a focus for anger at Sall's failure to rule out running for a third term next year.
Senegal's constitution only allows two terms, but some fear Sall will use a 2016 constitutional reform to reset his mandate, repeating a tactic used by other rulers to extend power elsewhere in the region. He has neither confirmed nor denied this.