The Capitol Hill office of Sen. John McCain, R-Ariz., is seen in Washington, July 20, 2017, after news that he has been diagnosed with brain cancer.
The Capitol Hill office of Sen. John McCain, R-Ariz., is seen in Washington, July 20, 2017, after news that he has been diagnosed with brain cancer.

CAPITOL HILL - News that Arizona Republican Senator John McCain has brain cancer triggered expressions of shock and an avalanche of well wishes across Washington and around the world on Thursday.

Capitol Hill witnessed an outpouring of support for a lion of the Senate.

"Senator McCain is an American hero," said Senate Majority Leader Mitch McConnell, a Kentucky Republican. "He's a hero to our conference, he's a hero to our country. Here in the Senate, he's a friend to almost all of us."

"From the bottom of my heart, I wish him and his family well," said Minority Leader Chuck Schumer, a New York Democrat. "So does every member of this chamber. The respect that this man has is broad and deep."

On Twitter, McCain promised he will be back soon.

McCain's absence felt

McCain's absence deprives the Senate of one of its strongest, most resolute voices and deprives Republicans of a vote they desperately need. The absence is particularly ill-timed for Senate Republicans, who could not muster the votes to reform health care even before the Arizonan's diagnosis.

"It's pretty clear that there are not 50 Republicans at the moment to vote for a replacement for Obamacare," McConnell said earlier this week, when Republicans assumed McCain would make a speedy return after what was initially described as surgery to remove a blood clot behind his eye.

Watch: US Senate Rallies Behind John McCain

With a slim majority — 52 seats in the 100-member chamber — Republicans will be one member short for an unknown length of time, just as they face intense pressure to make good on years of promising the end of Obamacare, which was President Barack Obama's signature legislative achievement.

"People are hurting. Inaction is not an option," President Donald Trump told Republican senators at the White House Wednesday. "And frankly, I don't think we should leave town unless we have a health insurance plan, unless we can give our people great health care."

A make-or-break Senate vote to begin debate on health care is expected next week. Democrats are united in opposition to the initiative, and some moderate Republicans as well as fiscal conservatives are not sold on their party's plan to replace Obamacare.

FILE - John McCain is administered to in a Hanoi,
FILE - John McCain is administered to in a Hanoi, Vietnam hospital as a prisoner of war in the fall of 1967.

?From Vietnam POW to statesman

A man who survived five years as a prisoner-of-war in Vietnam, John McCain's legendary grit and determination propelled him to six terms in the U.S. Senate and two White House bids.

Never one to sugarcoat words, McCain has not shied from criticizing the Trump White House.

"Obviously there is an administration that is in significant disarray," the Arizona senator remarked in February.

Before entering the White House, Trump had sharp words about McCain.

"He's a war hero because he was captured [in Vietnam]," Trump said of the senator in 2015. "I like people that weren't captured."

In recent days, the president has spoken in more conciliatory terms.

"And I can tell you, we hope John McCain gets better very soon because we miss him. He's a crusty voice in Washington. Plus, we need his vote," the president said.

Former Senator Edward Kennedy was stricken with the same form of cancer in 2008, yet was able to work for more than a year before succumbing to the disease.

Should McCain resign, Arizona's Republican governor would name a temporary replacement, keeping the seat in the Republican caucus.

But raw political calculations were not at the forefront of Senate action Thursday, as the chamber rallied behind a revered member.

"Oh God, our shield. ... Place your healing hand on Senator John McCain," Senate Chaplain Barry Black said as the chamber gaveled in Thursday. "Astound us with your power."