Absence in the Senate makes no heart grow fonder, given a delicate balance of power, 51-49, with Democrats holding a knife edge. Consider “DiFi,” Dianne Feinstein, a Democratic elder on her sickbed.

She’s been gone for going on 60 votes. Every chamber vote must be in person: no exceptions, not even for COVID-19.

The California senator’s absence is causing angst among her colleagues during a six-week bout of shingles. Once a regal force as a legislator, now a missing person, she makes no promises on when she’ll be back in Washington to resume her duties.

“Soon” brings no comfort to her side of the split. Feinstein, elected in 1992, will turn 90 in June. She is the oldest member of the Senate.

Private conversations about Feinstein’s frailty and memory loss are getting more common on Capitol Hill. Her mind seems clouded compared to her sharp former self.

The Senate Judiciary Committee cannot advance presidential nominees without her vote. So, a sense of frozen frustration builds among Democrats as San Francisco’s former mayor languishes from a painful disease.

Majority Leader Chuck Schumer, D-N.Y., may angle for Feinstein’s withdrawal from the key committee. No senator has publicly called outright for her resignation. Yet. A few House Democrats pressed for her exit, but senators live in their own orbit.

Sadly or selfishly in California, the recently widowed Feinstein cannot close the curtains on a brilliant career that included authoring an assault weapons ban and releasing a CIA torture report. Her reluctance to bow out tells you how hard politicians work for and cling to their laurels long after time is up.

Behind the bonhomie, the time, money and energy they invest in holding office is huge, unknown to most Americans.

Lawmakers pay a high price for power on center stage and it’s hard to let go. I know, I know. Besides, the Senate can be a great place to grow old. In fact, this is the oldest Senate we’ve ever had, according to the historian’s office.

In the event of an empty seat, Democratic Gov. Gavin Newsom would appoint Feinstein’s successor.

Two senators also missing in action just returned to the fray: Republican Leader Mitch McConnell of Kentucky and freshman Democrat Sen. John Fetterman of Pennsylvania. It’s worth discussing their return to work, to compare their cases with Feinstein.

Another octogenarian at 81, McConnell took a fall at a fundraiser and suffered a concussion this winter. He wryly noted on the floor Monday that being “hardheaded” served him well. He walked slowly with an uneven gait.

The truth is, I missed McConnell imposing some order and sanity on the party he leads. Wily like a fox, he knows the rules better than anybody and usually wins the fights he picks. To his credit, he despises former President Donald Trump.

Compared to Speaker Kevin McCarthy, R-Calif., McConnell is a voice of reason on the debt ceiling crisis before us. The Treasury needs to raise the limit to preserve our “full faith and credit” and avoid shaking the global economy.

Trump loyalist McCarthy is capable of drunk driving the nation to the brink of default for the first time. Maybe McCarthy is so bad that he makes McConnell appear better.

But how now. Republican whip John Thune of South Dakota looks lean and hungry when he sits near McConnell’s empty chair. After all, he’s the No. 2 Republican in Senate leadership — or likely succession.

Tall, bald and goateed Fetterman came back to the Capitol clad in his campaign black hoodie and gym shorts. Away since February, he was treated for severe depression at Walter Reed National Military Hospital.

A scrum of reporters awaited Fetterman’s return at the stately old carriage entrance. His casual attire made an odd contrast with the marble all around him.

At 53, Fetterman doesn’t have an aging issue, but a culture clash with formal splendor.

Clad in a suit and tie, he later showed up for a Senate floor vote, Sen. Bob Casey, D-Pa., standing steady by him. A sweet fleeting moment.

Back to Feinstein’s plight. She proposed a temporary removal from the Judiciary committee. Republicans refused. She counted many as friends, but that time is past, DiFi, partisanship is all.

Jamie Stiehm may be reached at JamieStiehm.com. Follow her on Twitter @JamieStiehm.