Rebecca Katz, a progressive political consultant based in New York who is not working for a 2020 candidate, said she believes that women and nonwhite candidates are scrutinized more than white male politicians, yet hopes that Ms. Harris will embrace bold ideas and tell more of her personal story even if it seems risky. Mo Elleithee, the former spokesman of the Democratic National Committee who now leads Georgetown University’s Institute of Politics and Public Service, said that much of the country is still unaware of Ms. Harris, and that she has time to refine a national narrative that resonates with many groups of Democrats.

Reviews of Ms. Harris’s book have been mixed, as critics have accused her of not adequately grappling with several controversial stances she took as California attorney general and others have characterized it as overly reliant on political clichés.

In the memoir, which was released simultaneously with a children’s book by Ms. Harris called “Superheroes Are Everywhere,” she repeatedly writes that she does not believe in “false choices.” This can mean both meaningful workers’ rights and a strong economy, she writes at one point, but she also applies the concept to police accountability and public safety.

“I know how hard it is for the officers’ families, who have to wonder if the person they love will be coming home at the end of each shift,” Ms. Harris writes. “I also know this: It is a false choice to suggest you must either be for the police or for police accountability. I am for both. Most people I know are for both. Let’s speak some truth about that, too.”

Sean Clegg, a longtime political adviser who is expected to play a senior role in any presidential campaign from Ms. Harris, said that if she ran she would discuss issues like income inequality, but that the message would be coupled with a call for partisan healing.

Paul Berkman, a 72-year-old New Yorker who attended the book talk, said he wished Ms. Harris talked about more policy ideas during her conversation, which was moderated by the poet Cleo Wade. Mr. Berkman said he left not knowing her answer to the “why-are-you-running-for-president” question every candidate faces.

“She seems like a likable person, but there’s so many candidates — I want someone to verbalize why it should be them,” he said.