Senator Dianne Feinstein to Retire at the End of Her Term

WASHINGTON — Senator Dianne Feinstein, Democrat of California, announced on Tuesday that she would not run for re-election in 2024 but would finish out her term in Congress, making official a retirement that was long assumed by her colleagues who had grown concerned about her memory issues and clearing the way for what is expected to be a costly and competitive Democratic primary for the seat she has held for three decades.

Ms. Feinstein, 88, has had acute short-term memory issues for years that sometimes raise concern among those who interact with her. She has never acknowledged the problems.

She said in a statement that she planned to “accomplish as much for California as I can through the end of next year, when my term ends,” meaning Gov. Gavin Newsom of California will not appoint a replacement to fill her seat.

Ms. Feinstein, a trailblazing Democratic power broker, these days struggles to recall the names of colleagues, frequently has little recollection of meetings or telephone conversations, and at times walks around in a state of befuddlement — including about why she is increasingly dogged by questions about whether she is fit to serve in the Senate representing the 40 million residents of California.

Some Democrats did not wait for her to announce her plans to jump into the race. Representatives Katie Porter and Adam B. Schiff, both Democrats of California, have started their 2024 Senate campaigns.