GEOFF BENNETT: The Senate returns to Washington next week without its oldest member, California Senator Dianne Feinstein.

And calls are growing louder for her to step down for good.

Earlier this week, the 89-year-old announced she would temporarily forfeit her position the Senate Judiciary Committee while she recovers from an infection, a move intended to allow committee business to resume.

But that did not satisfy critics, who say she's no longer fit to serve.

Congressional correspondent Lisa Desjardins has been following all of this and joins us now.

So, Lisa, catch us up on why Senator Feinstein has been out since February and why it matters now.

LISA DESJARDINS: She has been recovering from a shingles infection.

That is something that normally isn't a problem, but it has taken longer for her to recover than usual.

That happens with older Americans more frequently than others.

And it's not unprecedented for a senator to be out for two months.

But what is unprecedented now is the math of this situation.

Let's look at what it is for Senate Democrats right now.

They hold the Senate chamber with a 51-seat majority.

They hold the Judiciary Committee with 11 Democrats to 10 Republicans.

That is critical, because, without Feinstein, that committee is at a tie.

If it's a tie, Geoff, the Judiciary Committee can not pass on any judicial nominations.

And I don't know if anyone's noticed, but the Senate hasn't been doing anything else except for nominations.

Democrats wanted to get judge after judge after judge on the federal bench.

Without Feinstein, that entire thing is frozen.

She has requested to be replaced on that committee.

But that can't happen unless Republicans agree.

And my reporting is, it's not clear that they will do that next week.

So, Feinstein's absence really has major consequences for the Democratic agenda in the Senate.

GEOFF BENNETT: Well, a number of Democrats have said, the longer this persists, the greater the problem becomes, but there are some Democrats who are saying, look, she has to resign right now.

What's your reporting on that?

LISA DESJARDINS: Right.

So we have got her health condition now, but also questions that have been hovering about her abilities in general.

This week, two House Democrats say she should resign, one of them a California Democrat, Ro Khanna.

He said it is now clear that she no longer can fulfill her duties.

More notable, I think, today was this from a person closer to Dianne Feinstein.

Senator Amy Klobuchar raised concerns.

SEN. AMY KLOBUCHAR (D-MN): I want to see what happens in the next month or so.

We -- you give her that time to be able to come back.

But if she can't come back month after month after month, with this close Senate, that's not just going to hurt California.

It's going to be an issue for the country.

LISA DESJARDINS: There are a lot of unspoken layers here.

The charge here is that Senator Feinstein is mentally unfit.

I spoke to her the last week that she was here in February.

It was a normal conversation.

It was short, but normal.

Other reporters have had different experiences.

Notably, she did not seem to know when her retirement was announced.

But her office tells me that she is in charge.

She is daily speaking with them.

And my understanding is that, unless something changes, she does not plan to retire.

GEOFF BENNETT: Well, how does that compare with other senators you cover?

LISA DESJARDINS: Notable difference.

I can count on both hands -- I need both hands to say how many older male senators I have spoken to who have been confused, who haven't understood me, including one who called me, had a rambling conversation that was very confusing, that person no longer in the Senate.

But there is a question here about a double standard.

And House Speaker, former Speaker Nancy Pelosi raised this herself.

REP. NANCY PELOSI (D-CA): It's interesting to me.

I don't know what political agendas are at work that are going after Senator Feinstein in that way.

I have never seen them go after a man who was sick in the Senate in that way.

LISA DESJARDINS: Another layer here, of course, is the age of the Senate itself.

GEOFF BENNETT: Yes.

LISA DESJARDINS: Let's look at where things stand.

Right now, the current 118th Congress, the average age of U.S. senators is 64 years old.

I looked at the Department of Labor.

The average age in the U.S. work force, 42, much younger.

Another way of looking at this, a third of the current U.S. Senate is 70 years of age or older.

There is obviously number of senators that have been there a very long time.

It's a gerontocracy.

And there's a question of when things need to change hands.

Also, another senator over 80 years old, Mitch McConnell, he is recovering as well from a concussion he suffered.

He has been out for several weeks.

He is to return Monday.

GEOFF BENNETT: So what are the other - - the -- really the larger politics happening here around whether Senator Feinstein stays or goes?

LISA DESJARDINS: There's so much around this race for her seat.

Let's look at who's running, just the Democrats alone in California, a Democratic state, Adam Schiff, Katie Porter, Barbara Lee, three of the Democrats, most well-known House members, two of them the biggest fund-raisers.

That is a battle royal for House Democrats to try and get Feinstein's seat.

So there are political reasons that some Democrats would like her to retire, not just necessarily the good of the country, though that is what other Democrats say as well.

GEOFF BENNETT: Lisa Desjardins, thanks for sharing that reporting with us.

Have a great weekend.

LISA DESJARDINS: You too.