Pressure is mounting on Sen. Dianne Feinstein (D-Calif.) to step down as her prolonged absence from the Senate stymies Democratic business in the chamber with no clear end date.

Rep. Ro Khanna (D-Calif.) — closely followed by Rep. Dean Phillips (D-Minn.) — sent shockwaves from California to Washington on Wednesday when he said Feinstein should resign because the five-term senator is unable to carry out her responsibilities in her current condition. Feinstein, 89, has been absent from the Senate since early March when she was diagnosed with shingles.

In doing so, they became the first lawmakers to give voice to several years of whispered questions around the Capitol about Feinstein’s fitness to serve.

Feinstein responded with an acknowledgement that she would not be in the Capitol Monday when the Senate reconvenes after a two-week recess, and she requested to be temporarily replaced on the Judiciary Committee.

But that may not be enough for lawmakers who want to see her call it quits before her planned retirement at the end of 2024.

“It’s a step, but as has been reported, it’s not that simple,” Khanna said on CNN Thursday.

Khanna is the co-chair of Rep. Barbara Lee’s (D-Calif.) campaign to replace Feinstein in the Senate. Reps. Adam Schiff (D-Calif.) and Katie Porter (D-Calif.) are also vying for the seat.

Khanna, who passed on his own bid for Feinstein’s seat, told CNN he “felt an obligation to say what so many colleagues are saying in private,” and Phillips, who has argued for a new generation of Democratic leadership in Washington, declared that it is “a dereliction of duty” for the Californian to remain in the Senate.

“My intent was not to make a splash, it was simply to say publicly what so many know privately,” Khanna told The Hill on Thursday. “While Sen. Feinstein has had an extraordinary, distinguished career, she’s simply unable now to fulfill her duties.”

At least one House Democrat, however, has a less charitable reading of his remarks.

“It’s no secret the governor said he would appoint a black woman if there were ever a senate vacancy. Calling for Senator Feinstein to resign as she battles shingles is a cynical way for Barbara Lee’s sole California congressional endorsement Ro Khanna to try and force an appointment of Barbara Lee, who trails far behind the race in fundraising,” a House Democrat told The Hill by text message on Thursday.

Still, Feinstein’s absence has left Senate Democrats in a tough spot. They are down one body, which, to the chagrin of the caucus, has brought the Judiciary Committee — which is responsible for confirming judges — to an even split, leaving the majority party unable to advance partisan nominees to floor votes.

There are 14 judicial nominees who have appeared for Judiciary Committee hearings but have not received a vote from the panel. On top of that, the committee has had to cancel three markups for nominees, mostly because of Feinstein’s health troubles. The panel last voted to advance a nominee on Feb. 16.

It remains to be seen whether her request for a temporary replacement on the panel will insulate her from further calls to resign, or if the floodgates will burst open.

The answer could depend on whether Democrats are able to secure a replacement on the panel.

“Certainly, the floodgates are open after being relatively quiet for the past couple of months, but it all depends on what happens next week. What does she do if Senate Republicans don’t agree?” said Jim Manley, who served as a top aide to former Senate Majority Leader Harry Reid (D-Nev.) and former Sen. Ted Kennedy (D-Mass.).

Senate Majority Leader Chuck Schumer (D-N.Y.) said he will push for Feinstein to be replaced on the committee next week, but the process to do so is a tricky one with little precedent. 

Temporarily assigning another Democrat to the panel would mean revising the committee arrangements and organizing agreement established at the outset of the new Congress. Schumer is expected to try to bring up the resolution through unanimous consent.

If a single senator blocks it, however, it will be subject to a filibuster and need 60 votes — including Republican support — to pass.

Republicans are expected to discuss how to proceed on this issue in the coming days as they return to Washington from the recent two-week recess. None, including Senate Minority Leader Mitch McConnell (Ky.) who is returning from his own five-week medical leave, have said publicly how they would vote.

NBC News reported on Thursday that aides say Republicans don’t seem inclined to help Democrats regain a majority on the committee.

Feinstein has yet to lay out a timeline for her return, only saying she hopes to be back “as soon as possible.” 

In the meantime, the picture is complicated for Democrats who respect Feinstein as a lion of the Senate and a female trailblazer who has been at the forefront for 30 years. Her status, however, has made the situation “untenable,” according to Manley. 

Even before her latest illness, rumors had floated around the Capitol about Feinstein’s age, mental acuity and memory lapses. 

She stepped aside as the leading Democrat atop the Senate Judiciary Committee in late 2020, a move that followed intense criticism over her handling of the confirmations of Justices Brett Kavanaugh and Amy Coney Barrett to the Supreme Court.

Feinstein also declined to take on the position of Senate president pro tempore, usually reserved for the most senior member of the party in power.

In February, just an hour after she announced her retirement, she appeared momentarily confused and seemingly forgot she had just done so.

“No one’s happy to be talking about it, but more and more folks are coming to believe that something’s got to be done,” Manley said. “It never ceases to amaze me how much some of these folks cling to the Senate. For some, it’s their end all and be all. They couldn’t handle life without being a senator.”

Most of the drive to replace Feinstein sooner rather than when her term expires is coming from the progressive activist wing of the party, one that is less willing to stand by and wait their turn as other portions of the party has been, especially in the Golden State. 

“The last polls you’ve seen, voters have moved on from Dianne Feinstein. That’s the hard truth. The [California Democratic Party] didn’t support her last time she ran,” said Andrew Acosta, a Sacramento-based Democratic strategist, noting that Khanna himself ousted an incumbent House Democrat in a primary. 

“There’s a lot more people who are ready to run and not wait, and you’re seeing that across the board,” Acosta said.

Of course, Khanna is supporting Lee, who would seem to be in prime position to be appointed to Feinstein’s seat if she were to call it quits early. California Gov. Gavin Newsom (D) has vowed to name a Black woman to the seat. Los Angeles Mayor Karen Bass (D) was also considered a leading choice for the spot, but she just started her tenure atop the nation’s second largest city. 

The question, however, is whether Newsom’s choice would simply serve out the remainder of Feinstein’s term and not run for the spot, or plan to use the appointment to catapult them into the 2024 race.

“Is it a position of a caretaker? Or is it someone that’s in for the long haul and is going to run?” Acosta asked.

While Democrats have been weary of wading into the debate over Feinstein’s tenure, one prominent California liberal flocked to the senator’s defense: Rep. Nancy Pelosi (D-Calif.). The former Speaker — who is backing Schiff in the race — suggested that calls for Feinstein’s resignation were tinged with sexism.

“It’s interesting to me, I don’t know what political agendas are at work that are going after Sen. Feinstein in that way. I’ve never seen them go after a man who was sick in the Senate in that way,” Pelosi said.

Rep. Norma Torres (D-Calif.) sounded a similar note.

“Dear @SenFeinstein please get well soon. When women age or get sick, the men are quick to push them aside. When men age or get sick, they get a promotion. #WomensRights ARE #HumanRights,” she wrote on Twitter.

Hanna Trudo contributed.