The silence surrounding the empty seat on the Senate Armed Services Committee lifted suddenly and momentarily during a hearing Thursday.

Sen. Angus King, I-Maine, was questioning a nominee who could oversee Air Force weapons buying including the B-21 Raider, a future heavy stealth bomber with a secret price tag.

“You're going to be managing a very important program, and that is the B-21,” King said. “And if Sen. McCain were here, he'd be talking about accountability. He's always looking for who we can fire.”

The joke caused laughter but was also a poignant reminder.

McCain, 81, the fiery and seemingly tireless Armed Services chairman who is now battling brain cancer, was still at home in Arizona and absent from his committee’s first hearing of 2018.

The hearing Thursday was remarkable partly because of his absence. McCain, who was diagnosed with glioblastoma in July, has been a driving force on the committee since he took the gavel three years ago.

During hearings, he was known for regularly berating military officials over wasteful government spending, decrying 100-hour work weeks for Navy sailors, and grilling Pentagon nominees over evasive testimony.

McCain’s committee participation was uncertain for the first two weeks of the Senate session, and his staff was mum in the days leading up to the Thursday hearing on whether he would chair it. Sen. Jim Inhofe, R-Okla., who chaired the hearing and is likely next in line to lead the committee, has resisted talking about it.

There was no update on McCain’s status Friday, staff said.

McCain has stayed in Senate politics from afar. He issued a statement Friday saying he is “very pleased” with the new National Defense Strategy unveiled by Defense Secretary Jim Mattis.

“It gets the big decisions right, prioritizes the threats we face, and offers clear guidance for making tough choices,” McCain said.

Meanwhile, Armed Services, after an initial pause this month, is moving ahead with business despite uncertainty around McCain’s return to Washington.

The hearing Thursday may advance four Pentagon nominees. Armed Services has also announced two more hearings in the coming week.

Henry Kissinger, the former secretary of state and famed elder statesman, will testify along with George Shultz and Richard Armitage to Armed Services on Thursday about the U.S. National Security Strategy unveiled this month and global challenges.

The empty chairman seat during the nominations hearing also suggested an unspoken question: Will McCain return to Armed Services?

McCain spent the holidays in Arizona after being hospitalized at Walter Reed National Military Medical Center in December due to the side effects of chemotherapy. At the time, his staff said he was eager to return to work in Washington this month.

McCain’s close friend, Sen. Ted Kennedy, who was known as the “Lion of the Senate,” died of the same type of brain cancer in 2009. Kennedy curbed his Senate work during the last 15 months of his life but returned from time to time for key votes and hearings.

McCain had quickly returned to work after his diagnosis, often walking Senate halls surrounded by reporters after receiving chemotherapy treatment. By November, he was using a wheelchair to get around following a foot injury that required an orthopedic boot.

Sen. Lindsey Graham, R-S.C., one of McCain’s closest friends, said he visited the chairman in Arizona last week.

"I was very pleased with his progress. He's making progress,” Graham told CNN on Thursday. "We laughed a little bit. We cried a little bit. I admire him greatly, and I'm hoping he can come back and be with us.”