Sen. John McCain — political maverick, prisoner of war, unsuccessful Republican presidential aspirant, architect of campaign finance regulation, and star of the “Straight Talk Express” — died Saturday, succumbing to the most virulent form of brain cancer at age 81 after a year-long battle with the disease.

The Arizona senator’s office announced his passing in the late afternoon, only a day after his family had said that he had decided against continuing further treatments. “With the senator when he passed were his wife Cindy and their family. At his death, he had served the United States of America faithfully for 60 years,” the office said.

President Donald Trump expressed condolences to the McCain family, tweeting late Saturday, “My deepest sympathies and respect go out to the family of Senator John McCain. Our hearts and prayers are with you!”

McCain had not been in the nation’s capital since December, choosing to remain in Arizona where he could be close to his family, friends and doctors. He announced his diagnosis of stage 4 brain cancer last summer.

The son and grandson of four-star Navy admirals, McCain said in a memoir published earlier this year of his eventful life, “It’s been quite a ride. I’ve known great passions, seen amazing wonders, fought in a war, and helped make peace.”

He also said, “I’ve lived very well and I’ve been deprived of all comforts. I’ve been as lonely as a person can be and I’ve enjoyed the company of heroes. I’ve suffered the deepest despair and experienced the highest exultation. I made a small place for myself in the story of America and the history of my times.”

That last line was an understatement. From his five and a half years of imprisonment and torture in the infamous “Hanoi Hilton” during the Vietnam War through his subsequent election to the House of Representatives in 1982 and the U.S. Senate in 1987, during the Reagan era, and on through nearly three decades thereafter, McCain was a central figure in most of the major national political dramas that dominated headlines.

He won re-election to the Senate five more times, occupying the seat previously held by conservative icon Barry Goldwater. Then in 2000, McCain took on the supreme challenge in American politics — seeking the presidency.

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It was during that campaign, which he ultimately lost to then-Texas Gov. George W. Bush, that McCain dubbed his effort the “Straight Talk Express.” Accurate or not, it was a Trumpian maverick moniker long before the populist conservative Trump entered the presidential scene, and it stuck with McCain for the rest of his career.

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McCain tried again in 2008, coming from nowhere in March 2007 to win the Republican nomination to go up against a young Democratic colleague in the Senate, Barack Obama of Illinois, who defeated a third senator, Hillary Clinton of New York.

McCain’s 2008 vice presidential running-mate was then-Alaska Gov. Sarah Palin, who would go on the next year to become a Tea Party star and an early fixture in the populist conservative revolt that ultimately resulted in Trump’s 2016 nomination.

In a campaign that McCain was leading in some polls in late September, it appeared the maverick Republican was going to win the ultimate victory. But then the Wall Street crisis exploded. McCain suspended his campaign, but the move backfired when Obama stayed on the hustings. Obama went on to become the first black president.

Hard times and political defeats were nothing new to McCain by 2008. At one point early in his Senate career, it appeared his days on the national political scene would be brief, thanks to his involvement in the Keating Five scandal, one of the worst chapters of the savings and loan crisis that culminated during the presidency of George H.W. Bush.

McCain and four Senate Democrats had accepted campaign contributions from Charles Keating, chairman of the Lincoln Savings & Loan Association, which went bankrupt in 1989. A Senate Ethics Committee investigation ultimately cleared McCain of wrongdoing, but said he had displayed poor judgment in the matter.

Generally a conservative in his voting record, McCain endeared himself to the predominantly liberal national news media during the 2000 campaign with his aggressive support of campaign financial reforms opposed by most Republicans on constitutional grounds.

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McCain and Sen. Russ Feingold (D-Wis.) were the principal sponsors of the Bipartisan Campaign Finance Reform Act of 2002, which established limits on individual contributions to candidates for Congress and the presidency.

McCain also alienated many conservatives with his advocacy of liberal immigration reforms, and he further angered many on the Right with his opposition to the “enhanced interrogation techniques” that were branded torture by the media in the years following the 9/11 attacks by radical Islamic terrorists in New York and Washington, D.C.

Despite their bitter primary struggle in 2000 and McCain’s opposition to the CIA’s interrogation methods in the war against al-Qaida in Iraq and Afghanistan, McCain was an early and strong advocate of Bush’s decision to launch what became known in 2006 as “The Surge” of the Iraq War. That effort temporarily increased U.S. troop strength enough to virtually destroy the remaining opposition and clear the way for democratic elections in Iraq.

He was also a consistent advocate of strong national defenses, but McCain could be devastating to Pentagon executives and military leaders. Nowhere was that more vividly demonstrated than in his exposure of an Air Force plan in 2001 to pay Boeing more than $23 billion to lease air-to-air refueling tankers instead of buying them.

By the time McCain finished his campaign to kill the program, the Air Force dropped the lease plan and two key individuals — Boeing’s Mike Sears and Darleen Druyun, the chief Pentagon acquisition official on the lease deal — received prison sentences.

His vigilance against waste and fraud in the military bureaucracy wasn’t aimed only at big projects. In a 2015 report, McCain exposed a $50,000 Pentagon-funded study aimed at measuring the ability of elephants to detect bombs.

His popularity with the media was helpful to him; but his famous temper, which prompted stories even from his childhood of tantrums that lasted so long he blacked out, was not. Few were the Senate colleagues or aides who dealt with McCain who weren’t on the receiving end of at least one unpleasant encounter with his anger.

Even so, tributes immediately began coming in from all corners of the political and ideological spectrum as news of McCain’s passing was heard. White House senior adviser Kellyanne Conway, who was often on the opposing side of political conflicts involving McCain, offered in a tweet her “condolences and prayers to the McCain family. Gratitude and respect for John McCain, who served the nation honorably and courageously as a Navy Captain, POW in Vietnam, and U.S. senator. May he rest in peace.”

“I will forever remember his enduring passion for our great country. My heart & prayers are with his family.”

Rep. Darrell Issa (R-Calif.), the combative former chairman of the House Committee on Oversight and Government Reform, also tweeted, “John McCain was a patriot, statesman, fighter & someone I was honored to call a friend. From our travels to US military bases — to quiet moments in the Senate barber shop — I will forever remember his enduring passion for our great country. My heart & prayers are with his family.”

Former President George W. Bush, who defeated McCain in the 2000 Republican presidential primary, said in a statement, “Some lives are so vivid, it is difficult to imagine them ended. Some voices are so vibrant, it is hard to think of them stilled. John McCain was a man of deep conviction and a patriot of the highest order.”

He added, “He was a public servant in the finest traditions of our country. And to me, he was a friend whom I’ll deeply miss. Laura and I send our heartfelt sympathies to Cindy and the entire McCain family, and our thanks to God for the life of John McCain.”

Senate Minority Leader Chuck Schumer praised McCain’s “truth telling” and said he will offer a proposal to rename the Senate Russell Office Building after the Arizonan.

Vice President Mike Pence tweeted his praise for McCain, saying, “Karen and I send our deepest condolences to Cindy and the entire McCain family on the passing of Senator John McCain. We honor his lifetime of service to this nation in our military and in public life. His family and friends will be in our prayers. God bless John McCain.”

Obama, who defeated McCain in the historic 2008 contest, lauded his former adversary, saying, “We saw our political battles, even, as a privilege, something noble, an opportunity to serve as stewards of those high ideals at home, and to advance them around the world. We saw this country as a place where anything is possible — and citizenship as our patriotic obligation to ensure it forever remains that way.”

McCain had made plans for his funeral, including invitations to Bush and Obama to deliver tributes. There was, however, extreme hostility between Trump and McCain, so it is doubtful the president will attend the services.

The senator leaves behind his wife, Cindy, seven children, and five grandchildren. He also leaves his mother, Roberta McCain, who is 106.