SACRAMENTO—California’s Capitol roiled Monday as a lobbyist publicly accused a sitting legislator of sexually assaulting her at a Las Vegas party two years ago.

Pamela Lopez, flanked by lawyers from Levy Vinick Burrell Hyams at a press conference, said Assemblyman Matt Dababneh, D-Woodland Hills, followed her into a bathroom at a wedding that both were attending. Dababneh unzipped his pants and began masturbating, she said, urging her to touch him. Lopez said she refused and left the room feeling shaken.