WASHINGTON — She was once pressed to run for governor of California by President Bill Clinton. She was considered as a running mate to former Vice President Walter F. Mondale. And after the bitter 2008 Democratic primary, it was in her living room that former Senators Barack Obama and Hillary Clinton met to make peace.
These days, however, Senator Dianne Feinstein, the trailblazing Democratic power broker who has served in the Senate for 30 years, is far from the towering presence she once was on the American political stage.
At 88, Ms. Feinstein sometimes 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, according to half a dozen lawmakers and aides who spoke about the situation on the condition of anonymity.
On Capitol Hill, it is widely — though always privately — acknowledged that Ms. Feinstein suffers from acute short-term memory issues that on some days are ignorable, but on others raise concern among those who interact with her.
Ms. Feinstein is often engaged during meetings and phone conversations, usually coming prepared and taking notes. But hours later, she will often have forgotten those interactions, said the people familiar with the situation, who insisted that they not be named because they did not want to be quoted disparaging a figure they respect.
Some of them said they did not expect her to serve out her term ending in 2024 under the circumstances, even though she refuses to engage in conversations about stepping down.
A recent article in The San Francisco Chronicle, her hometown paper, reported that some of Ms. Feinstein’s colleagues believe she is mentally incompetent to serve. It recounted in brutal detail the signs of her decline on the job, an open secret that leading Democrats have quietly accepted as the status quo, but that some people close to her worry has become a spectacle that could tarnish her legacy.
One Democratic lawmaker who had an extended encounter with Ms. Feinstein in February said in an interview that the experience was akin to acting as a caregiver for a person in need of constant assistance. The lawmaker recalled having to reintroduce themself to the senator multiple times, helping her locate her purse repeatedly and answering the same set of basic, small-talk questions over and over again.
A second Democratic lawmaker who was also present said the conversation took place on a flight. In a statement, the second lawmaker described their own interaction with Ms. Feinstein as “pleasant and brief” and not otherwise out of the ordinary. (Last week, Ms. Feinstein was spotted flying in first class from San Francisco to Washington with her longtime housekeeper seated next to her.)
Pressed last week about Ms. Feinstein’s ability to serve, Senator Chuck Schumer, Democrat of New York and the majority leader, neither defended her nor tried to dismiss the issue.
“I’ve had a good number of discussions with Senator Feinstein,” he told reporters, “but I’m keeping them to myself.”
Annette Blum, a stepdaughter, said Ms. Feinstein had always been adamant about making her own decisions, whether or not the rest of the family agreed.
“We have the utmost respect for her life in public service and her career,” Ms. Blum said in an interview. “The decision is ultimately hers. We will all be there to support her in whatever decision she makes. The whole family feels this way.”
In 2018, when Ms. Feinstein decided to seek her sixth term in office, she was already facing questions about her age and mental acuity. But she insisted there were no issues — “My mind is fine,” she said in an interview at the time — and Mr. Schumer and the Democrats’ Senate campaign committee supported her re-election bid.
Ms. Feinstein’s supporters argue she did her party a favor by staying. The decision meant that Democrats “avoided an expensive open-seat race in California, so our state’s Democratic donors could focus on helping other candidates across the country,” said Jeffrey Millman, who served as her campaign manager that year. “Today, with her seniority, Senator Feinstein is an effective and indispensable leader for our state in the Senate.”
Most lawmakers argue that the only people who can tell a senator it is time to retire are family members. But Ms. Feinstein’s husband, the financier and Democratic megadonor Richard C. Blum, who passed away in February, shared his wife’s stubborn nature and unwillingness to consider an exit from the Senate. Last year, he was still telling friends she could run again in 2024.
When they would bring up questions about Ms. Feinstein’s ability to continue serving, he would shrug them off, according to two people who discussed the issue with him.
“What else is she going to do?” Mr. Blum would respond, they said.
After her husband’s death, Ms. Feinstein was under tremendous strain and there were conversations among those close to her about whether she might step away from the Senate. But in the months since, the people said, she has become set on continuing her work.
Ms. Feinstein has no plans to leave before the end of her term, a spokesman said.
“It’s true the last year has been difficult caring for my dying husband and grieving over his passing, but I’ve remained committed to achieving results and I would put my record up against anyone’s,” Ms. Feinstein said in a statement, noting that she secured millions of dollars in government funding for her state, among other achievements. “If the question is whether I’m an effective senator for 40 million Californians, the record shows that I am.”
Questions about her mental capacity have circulated for years. During the 2018 Supreme Court nomination hearings for Justice Brett M. Kavanaugh, people who worked with her said she struggled to remember the names of staff aides. In 2020, amid questions about her ability to lead the powerful Judiciary Committee, she was forced out as the top Democrat on the panel, an episode that people close to her said was deeply disappointing for the senator, who believed she had done the work, had waited her turn and was fully competent to lead the panel.
Ms. Feinstein’s fiercest defenders concede that she sometimes needs to be told the same information multiple times, and she herself admits to forgetting conversations at times. But her allies insist that, despite the realities of aging, she is in command of her office.
“She still calls the shots,” said Jennifer Duck, a former chief of staff to Ms. Feinstein. “If she didn’t call the shots, I’m sure lots of people would have helped her move onto something else.”
But in the United States Senate, there is a long tradition of powerful men who have failed to move onto anything else, even long after it was glaringly apparent that they could no longer function on their own.
In his final years in office, former Senator Strom Thurmond, Republican of South Carolina, who retired at the age of 100, could barely speak or hear and relied on staff members to help him on and off the Senate floor, where they could also be heard telling him how to vote.
Ms. Feinstein, people close to her said, is far more independent, and some argue that she is being held to a sexist double standard.
“She is a loyal and dutiful member of the committee,” said Senator Richard J. Durbin, Democrat of Illinois, who was chosen to step in as chairman of the judiciary panel after Ms. Feinstein was pushed aside.
Senator Sheldon Whitehouse, Democrat of Rhode Island, declined to comment about his interactions with Ms. Feinstein on the panel, where they serve together. “I’ll leave that to Senator Schumer,” he said.
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. She created Joshua Tree National Park, 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, she has become a target of progressive rage for giving Republicans, including former President Donald J. Trump, the benefit of the doubt — an approach that was common in the courtly Senate she joined in the 1990s, but one that has faded as political polarization has deepened. Some of her allies dismiss the questions about her mental capacity as attacks by Democrats who simply do not like Ms. Feinstein’s old-fashioned style.
To Ms. Feinstein, the questions about her fitness are mystifying and offensive.
She grows angry at the mention of the prospect that she might consider stepping down, pointing out that she still excels at securing funds for California, shows up to vote, attends hearings and leads the spending panel that controls energy and water programs.
Some lawmakers have privately raised red flags about Ms. Feinstein to Speaker Nancy Pelosi, who in a statement said it was “unconscionable” that the senator was “being subjected to these ridiculous attacks that are beneath the dignity in which she has led and the esteem in which she is held.”
Others appear to have grown impatient with the situation. At a hearing in January, Ms. Feinstein clashed with Senator Amy Klobuchar, Democrat of Minnesota, over a bipartisan antitrust bill that Ms. Klobuchar had put forward, asserting that the Biden administration was opposed.
“I have been told that,” Ms. Feinstein told Ms. Klobuchar, who pressed to know where her colleague had heard it. “You may not like it.”
Ms. Klobuchar responded, “Well no, I don’t like it at all, because I think that it’s not true.”
Despite such unpleasant moments, Ms. Feinstein’s former colleagues say the decision to end a long career in the Senate can be difficult.
Former Senator Tom Harkin, Democrat of Iowa, recalled going through “a lot of soul-searching” before deciding to forgo a re-election bid in 2013 after three decades in the Senate.
“You hate to leave all the things that go along with the office, and after all that amount of time, you’ve got seniority, and you’ve got great staff,” said Mr. Harkin, who was speaking from the Bahamas, where he owns a home and has taken up sailing. “I was satisfied that I got enough things done.”
Retiring, people close to Ms. Feinstein said, holds little appeal for her. She wants to keep working.