It was fifty years ago that U.S. Navy pilot John McCain endured five years of captivity and torture in what many have called hell’s inner sanctum – the Hanoi Hilton.  But now, the senior Senator from Arizona faces another fight for his life – and his odds of survival appear slim.

The news of 80-year-old McCain’s diagnosis with the most aggressive form of brain cancer sent shockwaves through the nation’s capital and cast a pall over the U.S. Senate at a time of great upheaval. The diagnosis of cancer came just hours after the Senate failed to reach consensus on a health care reform bill promised by the GOP for years.

The self-styled maverick has accumulated many a friend – and enemy – over his thirty years in the upper chamber, marked largely by a singular willingness to publicly criticize members of his own party, which has made him a favorite of the establishment media.  He is well known for his independence and toughness, and also for his streak of vindictiveness, most recently directed at the President after then-candidate Trump appeared to demean McCain’s status as a hero by saying he prefers those who are not captured.  McCain was also one of just three Republican Senators who voted against the signature George W. Bush tax cuts after Bush surrogates spread nasty rumors about him during the 2000 presidential race.  He has made many friends on the other side of the aisle.

McCain is one of the longest-serving members of the current Senate and was the GOP presidential nominee in 2008.  Having just been elected to a sixth term in the upper chamber last November, he has continued to serve as Chairman of the Senate Armed Services Committee.

But the outlook for McCain is now grim.

Glioblastoma multiforme is the most common and most deadly form of brain and nervous system tumor, typically killing half its victims within a year. Patients rarely survive more than three years.

It is the same type of tumor that killed Democratic Senator Edward Kennedy and, more recently, former U.S. Vice President Joe Biden’s son Beau.

No matter what people say about him, it is undeniable that McCain managed to survive what most humans could not.  He suffered serious injuries when his plane was shot down over Hanoi in 1967, and he endured brutal beatings by his captors that led to lifelong physical disabilities.  And yet, perhaps the greatest measure of his bravery was his refusal to accept an early release when fellow captives had been scheduled for liberation before him.

The question now is when – or whether – McCain might return to Washington for the final act of his long political career.  With big-ticket items – primarily health care and tax reform – hanging in the balance – not to mention the National Defense Authorization Act which is the primary responsibility of McCain’s Armed Services Committee – every Republican vote becomes vital.  And knowing McCain, he is not likely to give up the fight now any more than he did in Hanoi five decades ago.