From his involvement in the immigration reform effort, to the nomination fight over Obama’s defense secretary, former Sen. Chuck Hagel (R-Neb.), McCain is more relevant now than he has been since he carried his party’s banner in 2008. And his reemergence gives the war hero and former Vietnam prisoner of war an opportunity to be remembered at the end of his career for things other than a disappointing presidential run that associated him indelibly with former Alaska Gov. Sarah Palin, who he chose as his running mate.

McCain knows he is living out the closing chapters of a storied career. During our interview, he spoke frankly about his current role in politics, and his clashes with the Obama administration and members of his own party. And he expressed concern that he not overstay his welcome in the Senate, raising questions about whether he intends to run for reelection in 2016 at age 80.

But he is also a restless soul, who cannot stand still for long. McCain wrote in his 2002 book, “Worth the Fighting For,” that one of his favorite quotes came from his mentor, former Sen. John Tower (R-Texas). “Son, don’t let your shirttail hit you in the ass. Keep running,” Tower used to say. …

Nonetheless, stories asking different variations of the same question — “Who is the real John McCain?” — have exasperated McCain’s friends, supporters and staff. Mark Salter, McCain’s longtime confidant, adviser and co-author on many of his books, referred to it as “amateur psychoanalysis.”

“Circumstances have changed, but he really hasn’t,” Salter said.