John McCain
Republican presidential nominee Senator John McCain listens as he is being introduced at a campaign rally in Denver, Colorado Oct. 24, 2008. Reuters/Brian Snyder

Sen. John McCain of Arizona, a decorated Vietnam War veteran and former presidential candidate, died Saturday afternoon. He was 81.

McCain had been battling brain cancer for more than a year. His office had announced Friday that he was discontinuing medical treatment.

A U.S. Naval Academy graduate and the son of a four-star admiral, McCain had a well-documented story as a prisoner of war during Vietnam. In October 1967, his plane was shot down over Hanoi, and from there he was taken to the city’s infamous Hoa Lo prison. McCain would spend five-and-a-half years enduring torture at the prison, which was sarcastically referred to as the "Hanoi Hilton."

Considered a "maverick senator," McCain had served two terms as a House member and was later elected to the Senate in 1986. In 2002, he helped pass the McCain-Feingold Act, a landmark campaign-finance reform bill.

McCain ran an unsuccessful bid for the 2000 Republican nomination, falling short to George W. Bush. In 2008, he won the GOP nomination and then lost to Barack Obama in the general election.

McCain's family and closest friends were with him and his wife, Cindy, at their 15-acre ranch near Sedona, Arizona. His daughter, Meghan, said the task of her lifetime would now be "to live up to his example, his expectations, and his love."

"The days and years to come will not be the same without my dad - but they will be good days, filled with life and love, because of the example he lived for us," she wrote in a statement shared on Twitter.

President Donald Trump tweeted his condolences to the family of the senator, whom he had frequently criticized since he first launched his presidential campaign in 2015.

Obama also issued a statement on McCain's passing.

Condolences poured in for the senator's family on social media.

McCain had a reputation for being quick-witted and for his broad understanding of many issues.

1. “I fell in love with my country when I was a prisoner in someone else’s. I loved it for its decency, for its faith in the wisdom, justice, and goodness of its people. I loved it because it was not just a place but an idea, a cause worth fighting for. I was never the same again; I wasn’t my own man anymore; I was my country’s.” - During his Republican presidential nomination speech

2. "I wish Godspeed to the man who was my former opponent and will be my president. And I call on all Americans, as I have often in this campaign, to not despair of our present difficulties, but to believe, always, in the promise and greatness of America, because nothing is inevitable here." - From his 2008 concession speech

3. "Nothing in life is more liberating than to fight for a cause larger than yourself, something that encompasses you, but is not defined by your existence alone." – He wrote in his memoir, "Faith of My Fathers"

4. "I don't give a damn what the President of the United States wants to do or what anybody else wants to do. We will not waterboard. We will not torture... We will not torture people... It doesn't work, my friends. It doesn't work." - Said in November 2016

5. “People who hold certain institutional positions should have your respect until they lose it. But the rest of us mortals have to earn it.” -Esquire, 2000

6. “It is your character, and your character alone, that will make your life happy or unhappy. That is all that really passes for destiny. And you choose it. No one else can give it to you or deny it to you. No rival can steal it from you. And no friend can give it to you. Others can encourage you to make the right choices or discourage you. But you choose.” - From his book, "Character Is Destiny: Inspiring Stories Every Young Person Should Know and Every Adult Should Remember."

7. “Nothing, not the valor with which it is fought nor the nobility of the cause it serves, can glorify war. War is wretched beyond description, and only a fool or a fraud could sentimentalize its cruel reality.” - In a speech to the American Red Cross in 1999

8. “I don't have a complaint. Not one. It's been quite a ride. ... I made a small place for myself in the story of America and the history of my times." – he wrote in his new memoir, "The Restless Wave."

9. “I’m sure you’ve noticed, I never talk about my experiences in prison. I’ve known too many professional heroes in my life.” - New York Times, 2013

10. “Courage is not the absence of fear, but the capacity to act despite our fears.” - Fast Company, 2004