As a member of the so-called Gang of Eight, McCain helped craft a bill overhauling the nation’s immigration system that included a comprehensive path to citizenship for millions of undocumented immigrants. It passed in the Senate, but was not taken up in the House. Later in his career, he became a prominent voice among foreign policy hawks, advocating for a more aggressive U.S. approach to world affairs. His experience as a prisoner of war lent him credibility in opposing so-called enhanced interrogation techniques such as waterboarding.

McCain first ran for president in 1999 with a scrappy and upstart campaign known for its “Straight Talk Express” bus that promoted his reputation as a “maverick” who would do and say things other Republicans would not. He lost the race, however, to the establishment-backed George W. Bush, due in part to a bitter smear campaign that falsely claimed McCain had fathered a black child out of wedlock. Bush and his team denied involvement, but McCain suspected otherwise. 

His 2008 presidential run was more successful. After key wins in the New Hampshire and South Carolina primaries, and the flame-out of other challengers, including former Arkansas Gov. Mike Huckabee (R) and former Massachusetts Gov. Mitt Romney (R), both of whom would later go on to mount presidential bids in 2012, McCain finally won his party’s backing for president.

Facing freshman Sen. Barack Obama (D-Ill.), McCain cast himself as an experienced and sensible Republican, but his quixotic decision to select Alaska Gov. Sarah Palin (R) as his running mate also turned into a major liability as the political novice floundered time and time again under the spotlight. McCain was ultimately unable to prevail against a younger, charismatic candidate who promised change amid a harsh recession and the costly war in Iraq.

On Capitol Hill, the longtime lawmaker was celebrated for, among many noble qualities, his quick wit and good humor. He often sarcastically chided reporters to dismiss or make a point. He traded barbs with colleagues and was known to frequently repeat some of his favorite quips.

“After I lost [the 2008 election], I slept like a baby,” McCain has joked over the years. “Sleep two hours, wake up and cry. Sleep two hours, wake up and cry.”

In recent years, McCain took on the role of party statesman, but one who was fiercely critical of the Obama administration’s strategy with respect to renewed conflicts in the Middle East, Ukraine and Libya. Along with friend and colleague Sen. Lindsey Graham (R-S.C.), McCain advocated for committing additional U.S. troops on the ground to defeat Islamic State terrorists in Iraq and Syria.

In 2016, McCain easily won re-election to his sixth term in the Senate by defeating Democratic Rep. Ann Kirkpatrick. The longtime lawmaker faced a more difficult test with several challengers in the GOP primary, reflecting pent-up frustration with his time and record in Washington among several tea party groups that failed to oust him in 2010.

The following year, McCain played a pivotal role in opposing several Republican bills to repeal and replace the health care program known as Obamacare. In a surprise move that cemented his legacy, McCain cast a dramatic late-night vote against GOP legislation rescinding the law. He repeatedly urged Republican leaders to start over by including Democrats in a more open process.

Toward the end of his life, McCain appeared to have made peace with his approaching death. In his book The Restless Wave, an excerpt of which was published on Apple News on April 30, the senator said his current term would be his last.

“If I hadn’t admitted that to myself before this summer, a stage 4 cancer diagnosis acts as ungentle persuasion,” he wrote. “I’m freer than colleagues who will face the voters again. I can speak my mind without fearing the consequences much. And I can vote my conscience without worry.”

Asked last year during a CNN interview about how he hoped to be remembered, McCain said, “He served his country.” He added: “And not always right, made a lot of mistakes. Made a lot of errors. But served his country, and I hope you could add honorably.”

The senator is survived by his wife and seven children, including popular author and national radio personality Meghan McCain.