Three people who have visited with the senator in recent weeks or been briefed on her status say her diagnosis appears to have taken a heavy toll on her. Other confidants, including two who have seen or spoken with the senator, underscored that they are still hopeful she could serve out the nearly two years that remain in her term. But neither of those people, who addressed the sensitive matter on condition of anonymity, indicated they were confident she would be able to do so from Washington.

In a statement released late Wednesday after this story first posted, Feinstein did not identify an expected return date and said she has asked Majority Leader Charles E. Schumer (D-N.Y.) to temporarily replace her on the Judiciary Committee so that the panel could process nominations — a highly unusual move.

“I understand that my absence could delay the important work of the Judiciary Committee,” she said.

The California Democrat said she planned to return to Washington “as soon as possible once my medical team advises that it’s safe for me to travel,” and reiterated that she would work from home in San Francisco. “When I was first diagnosed with shingles, I expected to return by the end of the March work period. Unfortunately, my return to Washington has been delayed due to continued complications related to my diagnosis,” she said.

A spokesman for Schumer released a statement shortly thereafter saying that he would “ask the Senate next week to allow another Democratic Senator to temporarily serve on the Judiciary Committee.” In order to replace Feinstein on the committee, Democrats could either pass a resolution through a 60-vote threshold or seek unanimous consent, which would require the support of all voting Senators. It is expected that Schumer will pursue a unanimous consent request, according to a Senate Democratic aide.

Feinstein’s request for a temporary replacement on the Judiciary panel is an acknowledgement that her absence has already forced her party to change how they run the Senate, where Democrats can’t move President Joe Biden’s judicial picks without her vote. And in California, the emerging race to succeed Feinstein is in a holding pattern of its own thanks to the uncertainty about her future — and persistent chatter about whether Democratic Gov. Gavin Newsom might be forced to disrupt the contest by appointing her successor.

The senator, an iconic presence in the party who passed up its top spot on the Senate Judiciary Committee in 2020 amid speculation about her mental acuity, has kept word of her condition hush-hush. Her staff has been reticent to talk about her health even with other members of the California delegation, according to six Democrats familiar with the conversations.

It’s a delicate dynamic, one made even tougher by Senate Democrats’ 51-vote majority. And speculation about Feinstein’s future ratcheted higher after the recent departure of her chief of staff, David Grannis, who left for a new role at the Commission on the National Defense Strategy. James Sauls, a longtime aide on the Senate Intelligence Committee, has stepped into the chief of staff role, according to Russell.

While her illness has kept Feinstein from voting in the Judiciary panel to approve Biden’s nominees for the federal bench, effectively stalling those confirmations for now, it’s also being felt on the Senate floor. The California Democrat has missed nearly 60 votes since her shingles diagnosis in mid-February.

That lengthy absence has strained Democrats’ 51-49 majority in the chamber, with Sen. John Fetterman (D-Pa.) also absent for weeks while in treatment for depression.

Vice President Kamala Harris has broken several ties to confirm judicial nominees on the floor, but committee action has been postponed on multiple nominations in her absence. There are currently 14 pending judicial nominees who have had hearings but have not gotten a vote in committee.

“I’m anxious, because I can’t really have a markup of new judge nominees until she’s there,” said Sen. Dick Durbin (D-Ill.), the party’s No. 2 and the Senate Judiciary Committee chair told POLITICO late last month.

Durbin took the top Democratic spot on the panel in late 2020 after Feinstein ceded it following a firestorm of liberal fury with her cordial treatment of the GOP — and then-Supreme Court nominee Amy Coney Barrett.

Since then, pressure has mounted on Feinstein from some fellow Democrats to end her storied career on her own terms. Just this week, liberals began reupping their nudges for her to step aside; Rep. Jamaal Bowman (D-N.Y.) retweeted a post appearing to call for Feinstein to retire, though it’s not clear whether the move amounted to an endorsement of that stance. And on Wednesday, shortly after this item was posted, Rep. Ro Khanna of California, did the same, as did Rep. Dean Phillips of Minnesota.

The longest-serving woman in Senate history said in February she would not seek another term but vowed to complete her current one.

Days after that announcement, the shingles sidelined Feinstein.

The race to replace the trailblazing California political giant is already crowded, with House Democratic Reps. Adam Schiff, Katie Porter and Barbara Lee battling for the seat that hasn’t been vacant in more than 30 years. Complicating their emerging rivalry is Newsom’s 2021 commitment to nominating a Black woman for the Senate should Feinstein resign.

If he sticks to that promise, it would put a finger on the scale for Lee — who, if appointed to serve out the rest of Feinstein’s term, could run for a full term next year with the advantage of incumbency.

California is one of the 36 states that allow the governor to appoint a senator to hold the seat until the next regularly scheduled statewide election. However, should an appointment happen too close to March 2024, experts said the Senate election could not be consolidated with the primary.

Nicholas Wu, Sarah Ferris and Daniella Diaz contributed to this report.