COLUMBUS, Ohio—House Democrats filed articles of impeachment Tuesday against scandal-scarred Attorney General Marc Dann, a fellow Democrat who could become the first official impeached and convicted in Ohio in two centuries.

The lawmakers’ resolution outlines nine counts alleging that Dann should be impeached for gross neglect of duty, gross immorality and obstruction of his office’s investigation that found an employee was sexually harassed by a top aide.

On May 2, Dann admitted an extramarital affair with an employee that he said contributed to an atmosphere leading to the sexual harassment claims. Three aides were forced out in the harassment investigation, which showed that management encouraged a casual work environment with frequent profanity and inappropriate interactions with subordinates.

Removing Dann from office would require support from Republicans, who control the Legislature, and a Senate trial. Ohio has not used the impeachment process since 1820, and 1808 was the last time someone was impeached and convicted.