Senator Dianne Feinstein to Retire at the End of Her Term

Ms. Feinstein’s stepdaughter, Annette Blum, said in an interview on Tuesday that she was “very proud of her long and impactful career” and that the family agreed that “this is the time for her to pass the torch.”

Some California Democrats did not wait for Ms. Feinstein to announce her plans to start campaigning for her seat. Representative Katie Porter, who flipped a previously Republican district in Orange County in 2018 and has earned Democratic accolades for her sharp questioning of corporate executives in congressional hearings, was the first to announce her campaign last month. Representative Adam B. Schiff, a former leader of the House Intelligence Committee and the manager of President Donald J. Trump’s first impeachment trial, entered the race a couple of weeks later.

Representative Barbara Lee, a progressive stalwart from the Bay Area, is expected to announce her candidacy by the end of the month. Representative Ro Khanna is seen as another possible candidate.

The Republican field is less clear. In California, all candidates run on the same primary ballot regardless of party, and the top two advance to the general election, so two Democrats could potentially face each other in November 2024.

Ms. Feinstein said Tuesday she would hold off on issuing any endorsement in the race, at least for a few months.

Over a half-century career in politics, Ms. Feinstein rose from a member of the San Francisco board of supervisors to the heights of Democratic power. As a senator, she helped create Joshua Tree National Park in Southern California, wrote the 1994 assault weapons ban and, as the detail-oriented, hard-charging chairwoman of the Intelligence Committee, produced the 6,700-page torture report on the excesses of the war on terrorism.

In recent years, however, Ms. Feinstein has been more sidelined. In 2020, amid questions about her ability to lead the powerful Judiciary Committee, she was forced out as the top Democrat on the panel. She was deeply disappointed by the move, according to people close to her, who said she was fully competent to lead the panel and had dutifully waited her turn.