Mr. Silver, a Manhattan Democrat, said that he had decided to censure Mr. Lopez after the Assembly’s ethics committee — made up of four Democrats and four Republicans — ruled unanimously that claims that Mr. Lopez had verbally and physically harassed the employees were credible. “There were multiple incidents of unwelcome physical conduct toward one complainant, wherein you put your hand on her leg, she removed your hand, and you then put your hand between her upper thighs, putting your hand as far up between her legs as you could go,” Mr. Silver wrote, describing the committee’s findings.

He also said, “There was pervasive unwelcome verbal conduct by you toward both complainants from early June 2012 until the time they made complaints of sexual harassment in mid-July 2012, including repeated comments about their physical appearance, their bodies, their attire, and their private relationships.”

He said that Mr. Lopez “required” one of the women to travel with him to Atlantic City last month, where he attempted to kiss her, and that “she struggled to fend you off before you stopped, and that on the drive back from Atlantic City you again put your hand between her legs.”

Kevin Mintzer, a lawyer for the two women, said in a statement that “the complainants’ experience working for Mr. Lopez was a terrible ordeal.” The statement continued, “His behavior toward them was both unlawful and morally reprehensible.” Neither Mr. Silver nor Mr. Mintzer named the women.“The sanctions imposed in this matter are substantial and fully warranted,” Mr. Mintzer added. Mr. Mintzer said his clients had not decided whether to sue, saying only, “We’ll evaluate and determine next steps.” But, he said, “Mr. Lopez should resign his office immediately.”

The Assembly has faced a string of sexual harassment allegations in recent years, and for Mr. Silver it is a particularly sensitive topic. In 2003, he faced accusations that he did not respond aggressively to rape allegations against a former top Assembly aide, J. Michael Boxley, who pleaded guilty that year to sexual misconduct. Two years earlier, an Assembly employee had brought a complaint of sexual assault against Mr. Boxley to the Assembly leadership, but the investigation was closed without action.

Since that time, the Assembly has confronted other sexual misconduct concerns. In 2006, Assemblyman Ryan Karben, a Democrat from Rockland County, resigned amid claims that he watched pornography with three interns. In 2007, Assemblyman Mike Cole, a Republican from western New York, was removed from his post as ranking member of the Assembly Committee on Alcoholism and Drug Abuse after revelations that he had slept at the home of a 21-year-old female intern after a night of heavy drinking. And in 2008, Assemblyman Sam Hoyt, a Buffalo Democrat who now works for Gov. Andrew M. Cuomo, had an affair with a former intern.