But Ms. Jackson Lee’s case most resembles that of Representative Elizabeth Esty, a Connecticut Democrat who did not seek re-election last year over what she called her failure to protect women on her staff from sexual harassment and threats of violence from her former chief of staff.

As laid out in the complaint, the case dates to October 2015, when the woman, then 19 and a student at Howard University in Washington, spent the fall semester as an intern at the Congressional Black Caucus Foundation, an influential nonprofit linked to the Congressional Black Caucus that promotes African-American career advancement through internships, seminars and policy research. She says that the internship coordinator took her out drinking one night and then back to his apartment where he forced her to perform oral sex and other unwanted sexual acts. The woman could not remember parts of what occurred during the encounter, the filing says.

The woman spoke with the internship coordinator the next day, who denied they had sex. When she met with representatives of the foundation, they placed him on leave. A foundation official, speaking under the condition of anonymity to discuss the ongoing legal case, said the foundation fired him after the 2015 incident for drinking with a minor. The internship coordinator denied to the foundation that he had any inappropriate sexual contact with the woman.

The woman initially pursued legal action, but did not bring a lawsuit at the time, and police did not bring charges, according to the complaint.

About two years later, after she graduated from Howard, the woman was hired by Ms. Jackson Lee’s office, where she helped manage the congresswoman’s communications and drove her around the capital, among other duties. When it appeared that Ms. Jackson Lee might hire the former internship coordinator to work in the office, the woman told her chief of staff, Glenn Rushing, that she had a “prior situation” with the prospective colleague, the complaint says. Mr. Rushing indicated he would not be hired.

A short time later, the woman saw a text message to Ms. Jackson Lee from A. Shuanise Washington, the foundation’s chief executive, saying that she had learned of the woman’s position with the congresswoman and had some “background on her” to share with the congresswoman, the complaint says. The woman saw the text messages as a “clear reference” to the earlier claims she had made to the foundation.

In March 2018, the woman told Mr. Rushing that she planned to resume legal action against the foundation and asked to speak with Ms. Jackson Lee about it. The meeting never took place, and the woman claims Ms. Jackson Lee refused a personal request to speak. Two weeks later, she was fired.