WASHINGTON — Sen. John McCain, the 2008 Republican presidential nominee, Vietnam prisoner of war and political maverick in Congress for more than three decades, has been diagnosed with an aggressive type of brain tumor.

The 80-year-old Arizona lawmaker has glioblastoma, according to doctors at the Mayo Clinic in Phoenix, where McCain had a blood clot removed from above his left eye last Friday. According to the American Brain Tumor Association, 12,000 people a year are diagnosed with glioblastoma. The American Cancer Society puts the five-year survival rate for patients over 55 at about 4 percent.

The senator and chairman of the Armed Services Committee had been recovering at his Arizona home. His absence forced Majority Leader Mitch McConnell, R-Ky., to delay action on health care legislation.

South Carolina Sen. Lindsey Graham said he spoke to McCain late Wednesday and he said: “Yeah, I’m going to have to stay here a little bit longer, take some treatments. I’ll be back.”

Colleagues offered support. “Senator John McCain has always been a fighter. Melania and I send our thoughts and prayers to Senator McCain, Cindy, and their entire family. Get well soon,” President Donald Trump said.

Former President Barack Obama tweeted: “John McCain is an American hero & one of the bravest fighters I’ve ever known. Cancer doesn’t know what it’s up against. Give it hell, John.”

McCain survived the July 1967 explosion on the USS Forrestal that killed 134 sailors; the October 1967 shoot-down of his Navy aircraft; and 5 1/2 years in a North Vietnamese prison.

“The Hanoi Hilton couldn’t break John McCain’s spirit many years ago, so Barbara and I know — with confidence — he and his family will meet this latest battle in his singular life of service with courage and determination,” said former President George H.W. Bush.