That means no freewheeling press conferences or TV appearances with partner-in-crime Sen. Lindsey Graham, R-S.C., a frequent travel companion with McCain on congressional delegations that ranged from Eastern Europe to Southeast Asia.

("This disease has never had a more worthy opponent," Graham told reporters asking about McCain's diagnosis at the Capitol on Wednesday.)

No McCain means no more thunderous stemwinders about what he considered abuses by the big contractors that sell military hardware to the Defense Department — not that he spared himself and his colleagues from criticism, either.

In 2011, McCain added his own corollary to President Dwight Eisenhower's warning about the power of the Pentagon and its contractors. McCain warned that the real problem was what he called the "military-industrial-congressional complex."

"To be clear, the military-industrial-congressional complex does not cause programs to fail," McCain said from the floor of the Senate. "But it does help create poorly conceived programs, programs that are so fundamentally unsound that they are doomed to be poorly executed. And it does help keep them alive — long after they should have been ended or restructured."

All the same, McCain's prescription never was to starve the beast. He mocked Trump's budget proposal that called for increasing defense spending as far too little compared with what he argued the Pentagon actually needs.

Trump himself also has been a frequent target: It was McCain who reportedly passed the infamous, unverified dossier about Trump, compiled by a former British intelligence officer, to then-FBI Director James Comey. McCain told reporters that he thought America's international leadership under Obama — which McCain excoriated at the time in blistering terms — still was better than under Trump.

And a Washington without McCain means a palpable vacancy at the Senate Armed Services Committee of which he is chairman and on which he has been a mainstay for years.

McCain has used his perch to advocate for more, ever more funding each year for the Defense Department, which he argued was left in bad shape after its Iraq War peak in spending. He has a reputation for crankiness, sometimes horsewhipping witnesses — either Pentagon leaders or nominees to join its ranks — if he does not find their answers satisfactory.

Last month, McCain lost his patience when Trump's choice to serve as deputy defense secretary, Patrick Shanahan, responded to a question by promising to look into it further.

"Mr. Shanahan, you're not making me happy," McCain said. "I'm not going to sit here and watch you duck every question and expect that everything is going to go smoothly. It's not."

Before that, McCain terrorized Navy Department witnesses who appeared before the committee to defend their overbudget, long-delayed littoral combat ship program. In December, he raged about a disastrous engineering breakdown aboard the USS Fort Worth that left it stranded at its pier. McCain demanded to know who was responsible.

Vice Adm. Thomas Rowden, at the witness table, said that he was.

"Should you be in your job?" McCain asked. (Rowden said yes.)

The chairman's colleagues on the Armed Services Committee said late Wednesday that they would be pulling for him as he confronts his cancer treatment. Ranking member Sen. Jack Reed, D-R.I., cited McCain's "indomitable spirit."

As senators and staff members prepare for their hearing scheduled for Tuesday about the prospects for building a 355-ship Navy, however, they do so with the knowledge that Chairman McCain might not be there to gavel it into session.

Or he might. McCain wrote Thursday on Twitter that Washington hasn't seen the last of him yet.

"I greatly appreciate the outpouring of support," he said. "Unfortunately for my sparring partners in Congress, I'll be back soon, so stand-by!

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