Jessica Ramos, a progressive New York State senator from Queens, announced early Friday that she was entering the race to unseat Mayor Eric Adams in next year’s Democratic primary.

Ms. Ramos is the fourth prominent Democrat to challenge Mr. Adams, whose administration faces numerous federal investigations, including one that led to the resignation on Thursday of New York City’s police commissioner.

Ms. Ramos said in an interview that the investigations of the mayor and his inner circle were troubling, and she used her campaign kickoff video to focus on Mr. Adams’s credibility.

“You’ll never have to wonder who I’m working for or who is paying me,” Ms. Ramos said in the video, as news footage of the investigation into Mr. Adams’s campaign is displayed. “We need to bring that trust back to City Hall.”

Ms. Ramos said she would center her campaign on improving life in the city and making it more affordable, pointing to her efforts in Albany on issues like raising the minimum wage.

“I feel that we are at a critical juncture where New Yorkers more than ever before can’t afford to live here and don’t see New York City as the vehicle to realize their American dream, and that’s a problem,” she said in the interview.