WASHINGTON — Arizona Sen. John McCain has discontinued medical treatment for an aggressive form of brain cancer, his family said Friday, likely indicating the war hero, presidential nominee and longtime leading lawmaker is nearing the end of his life.

McCain has surpassed expectations for survival, but “the progress of disease and the inexorable advance of age render their verdict,” the family said. “With his usual strength of will, he has now chosen to discontinue medical treatment.”

The six-term GOP senator, who would turn 82 next week, has been away from the Capitol since last December. If he should resign his seat or die soon, Republican Arizona Gov. Doug Ducey would name a replacement to serve until the 2020 election. The winner of that election would serve the remainder of McCain’s term through 2022.

In more than three decades in Congress, McCain became known as a political maverick willing to stick to his convictions rather than go along with party leaders — an independent streak that has drawn a mix of respect and ire.

Most recently, he has been a thorn in the side of President Donald Trump, keeping up his criticism of the White House even while undergoing severe medical treatment in Arizona.

In July, he issued a searing rebuke of Trump’s summit with Russian President Vladimir Putin, calling it a “tragic mistake” and “one of the most disgraceful performances by an American president in memory.”