The allegations stand in contrast to Gillibrand’s record as an advocate for women’s causes who has battled sexual harassment in the workplace, a message she has made central to her candidacy for the Democratic presidential nomination.

The staff member’s resignation included a letter she wrote to Gillibrand and two top aides in August in which she describes frustration over the office’s response to allegations of harassment and intimidation against the co-worker, Abbas Malik, a former special assistant to the New York senator.

The aide had accused Malik of making unwelcome advances toward her, as well as inappropriate misogynistic remarks about female colleagues and potential hires, Politico said. The woman was not identified by the news organization.

“I felt defeated, not just from the humiliation and pain that the harassment had brought me, but that in attempting to seek appropriate disciplinary actions for my harasser, my experience was devalued. I was devalued,” the aide said in her resignation letter.

Malik, who served primarily as a driver for Gillibrand, could not immediately be reached for comment. His recent firing followed the emergence of a new allegation, according to a member of Gillibrand’s staff.

Speaking with reporters outside the Capitol on Monday, Gillibrand asserted the woman’s complaint was taken seriously.

She said her office had investigated the allegations immediately “and did a professional and thorough investigation that was taken very seriously from the beginning.”

Malik had served two tours in Iraq and was at one point assigned a title related to military affairs, but his primary responsibility remained as a driver.

An aide to Gillibrand, who asked not to be identified to discuss internal matters, said an investigation into the staffer’s complaint was initiated within 42 minutes after she filed it in July. Seven staffers were subsequently interviewed.

After the investigation confirmed unprofessional behavior, the office rescinded Malik’s promotion and warned him that any additional misbehavior would result in his firing.

This article originally appeared in The New York Times.