Howard Brookins III, who was president of the George Washington University Student Association, stepped down from his position Sunday due to mental health challenges and amid sexual assault allegations, which he denies, according to a letter Brookins sent to student government leaders and university administrators that was published by The GW Hatchet, the student newspaper.

A female student at the university accused Brookins on Twitter of groping her without her consent while he was under the influence of alcohol. Several members of the Student Association called for his resignation earlier this month in response to the allegations and the “turmoil” Brookins caused in student government.

Brookins called the allegations “unsubstantiated” and said he “unequivocally and steadfastly” denies that he sexually assaulted the student. He also wrote that he has “struggled with alcohol abuse” throughout his time at GW and recently discovered he has a mental illness, for which he is now seeking help.

“There have been rumors, people perpetuating lies, and the GW Hatchet has run stories about me with unsubstantiated allegations, and I refuse to comment on speculation,” his letter said. “I think it is important to move on without me. For my health and so many other reasons, I tender my resignation from the SA effective immediately. I believe this is the best course for the SA to regain its focus on student affairs and not petty stories.”