Williams, 52, drew scrutiny last year as the lone Democrat cosponsor of a corruption-tainted nuclear plant bailout bill and for accepting $12,000 in contributions from FirstEnergy Corp., which authorities say secretly funded a $60 million bribery scheme to get the legislation approved.
The nuclear plant subsidies approved in 2019 have since been repealed.
Williams pleaded guilty in 2014 to two misdemeanors for selling Ohio State football tickets to a lobbyist from the payday lending industry that were purchased by her campaign. She received a suspended six-month sentence and was fined $2,225, the same amount the tickets were sold for.
Three other state lawmakers were convicted in cases tied to an investigation of payday lending lobbying activity at the Ohio Statehouse.
Williams was first elected to the Senate in 2014 and was reelected in 2018. She cannot seek reelection because of term limits. She previously served four, two-year terms as a state representative.