Senator Dianne Feinstein is said to be "working from home and resting comfortably" after undergoing a voluntary operation to have a pacemaker installed Tuesday afternoon, just hours after the 83-year-old senator was grilling Attorney General nominee Sen. Jeff Sessions at his Senate confirmation hearing. According to a statement published by her office, "The 90-minute, non-emergency procedure at George Washington University Hospital went smoothly and she will return to a full schedule very soon."

Also, Feinstein's reps add that the the decision to undergo the procedure "was made after consulting with her doctor and was undertaken out of an abundance of caution."

As KQED reports, Feinstein's press secretary has declined to provide any further details beyond that.

The AP notes that Feinstein's senate seat is up for reelection in 2018, but thus far the stalwart senior senator from California has not indicated any plans to retire. She has been serving in the Senate since 1993.

She remained her feisty, frowning self at Sessions's hearing on Tuesday, giving the opening remarks in her role as the ranking member of the Senate Judiciary Committee. She began by introducing some African-American Californians in the room, including Congresswoman Barbara Lee and former SF supervisor Reverend Dr. Amos Brown, and by saying that it was going to be especially "difficult" to vet a fellow senator with whom she'd worked for many years for a new role.

"As attorney general, his job will not be to advocate for his beliefs," she said at the hearing. "Rather, the job of the attorney general is to enforce federal law, even if he voted against a law, even if spoke against it before it passed, even if he disagrees with the precedent saying that the law is constitutional."

She called the job "an awesome responsibility and an enormous job," asserting that Sessions was not going to be allowed to simply do the President's bidding, and she quoted Abraham Lincoln's attorney general, Edward Bates, who said, "[t]he office I hold is not properly political, but strictly legal, and it is my duty above all other ministers of state to uphold the law and to resist all encroachments from whatever quarter."

Read her full opening remarks here.