A Sacramento lobbyist broke her silence Monday, filing a formal complaint with the Assembly that names the lawmaker she said cornered her in a bathroom last year and masturbated in front of her.

Pamela Lopez accused Assemblyman Matt Dababneh, D-Encino (Los Angeles County), of pushing his way into a bathroom with her last year and trying to get her to touch his exposed genitals. Dababneh quickly denied the allegations, claiming they are false.

Lopez initially declined to name the lawmaker when she first spoke to the news media about the alleged incident in October, saying she didn’t want the attention to be on one bad actor and that she feared her lobbying firm would lose business.

But on Monday, at a news conference with her lawyer, she said she decided to name the assemblyman — and file a formal complaint against him — after assurances from leaders in the Assembly that her allegations will be taken seriously and that she won’t be retaliated against.

“There is strength in numbers, and I want women to know that you can lawyer up and there are good people who will represent you and protect you,” Lopez said. “I’m putting this in the hands of the Legislature. Matt Dababneh has abused his power.”

Assemblyman Ken Cooley, D-Rancho Cordova (Sacramento County), head of the Rules Committee, which oversees human resources for the Assembly, said an outside investigator will be hired for the case and suggested Lopez file a police report because the “allegation is criminal in nature.”

Jean Hyams, Lopez’s lawyer, said her client had not decided whether to file a complaint with police.

Dababneh issued a statement denying the allegations: “I affirmatively deny that this event ever happened — at any time. I am saddened by this lobbyist’s effort to create this falsehood and make these inflammatory statements, apparently for her own self-promotion and without regard to the reputation of others. I look forward to clearing my name.”

His lawyer, Patricia Glaser, had sent Lopez a “cease and desist” letter on Friday, threatening legal action if she named him.

Along with Lopez, a second woman, Jessica Yas Barker, spoke at the news conference, saying she was subjected to sexual harassment by Dababneh when he was a congressional staffer for Rep. Brad Sherman, D-Sherman Oaks (Los Angeles County). Barker said Dababneh would routinely make inappropriate sexual comments and brag about sexual encounters with other women. She also said he would comment on her appearance, refer to her as “Ellen” — a reference to comedian Ellen Degeneres — and tell her she dressed like a lesbian.

Barker said she has already experienced retaliation from those who knew she was coming forward with allegations against Dababneh.

“There have been some really nasty things put out about me that are not true,” Barker said.

A third woman who was not at the news conference and who spoke to The Chronicle on condition that her name not be published said she left her job as a legislative staffer for Dababneh because the assemblyman would routinely make detailed sexual comments about other women that made her uncomfortable.

“He was creepy,” the woman said. “That’s why I quit. I was taken aback by his behavior.”

Jonathan Bash, a past president of the Bruin Democrats at UCLA from 2011 to 2012, wrote on Twitter and in a follow-up email to The Chronicle that it was common practice in the college Democratic club to warn women not to intern in Dababneh’s office or go to events with him. The Bruin Democrats’ current president, NJ Omorogieva, declined to comment.

Debabneh is a UCLA graduate.

The allegations against Dababneh come after hundreds of women signed an open letter Oct. 17 calling for an end to pervasive sexual harassment and sexual misconduct in the state Capitol.

The Legislative Women’s Caucus said in a statement Monday that an independent and thorough investigation is needed where the findings are made public.

“If the investigation finds that these allegations are likely true, there must be swift and transparent consequences for this type of behavior,” said caucus chair Assemblywoman Cristina Garcia, D-Bell Gardens (Los Angeles County) and vice chair state Sen. Connie M. Leyva, D-Chino (San Bernardino County), in a statement.

Assemblyman Raul Bocanegra, D-San Fernando Valley (Los Angeles County), resigned from his seat amid several allegations of sexual misconduct. State Sen. Tony Mendoza, D-Artesia (Los Angeles County), was stripped of his chairmanship until an investigation into sexual misconduct is completed.

Previously, after Lopez spoke about the incident without naming the lawmaker, Assembly Speaker Anthony Rendon, D-Paramount (Los Angeles County) called the allegation horrifying and noted that it is also a crime. Rendon said at the time that if the lawmaker turns out to be an assemblyman, “we will contract with an outside firm so there can be an independent investigation.”

“If he is found to have committed this assault or any similar harassment, I will ask for his immediate resignation and move for his expulsion if he refuses to resign,” Rendon said.

Rendon’s office did not immediately respond to a request for comment on Monday.

Lopez said the incident happened on Jan. 16, 2016, in Las Vegas at a party for a mutual friend who was getting married.

She said she did not have more than a brief conversation with Dababneh before he pushed his way into a bathroom with her.

She said Dababneh kept telling her to touch his genitals. She said she refused, instead pressing herself against the furthest wall in the bathroom.

Lopez said she initially indicated the incident happened in Sacramento, explaining that she worried that naming the Las Vegas location and time frame would have made it clear who the person was when she did not plan to name him.

“How the Assembly responds to Ms. Lopez’s report is a test of whether it is a body governed by law, or one that considers itself above the law,” said Hyams.

Melody Gutierrez is a San Francisco Chronicle staff writer. Email: mgutierrez@sfchronicle.com Twitter: @MelodyGutierrez