I’ve opposed many of John McCain’s public policy pronouncements over the years. None of that opposition, though, has stood in the way of my admiration for him as a dedicated public servant who brought a hero’s stature to his service in the U.S. Senate.

Sen. McCain, the Arizona Republican, is now in the fight of his life.

Doctors removed a blood clot from near his eye and now have revealed that the veteran lawmaker is suffering from an aggressive form of brain cancer.

His daughter Meghan calls him the “toughest person” she’s ever known. Tributes have poured in from throughout the nation, across the political chasm that divides the nation.

Donald Trump and his wife, first lady Melania Trump, sent their  “thoughts and prayers.” Former Presidents Clinton and George H.W. Bush sent their heartfelt prayers as well.

Barack Obama, with whom Sen. McCain tussled as the two men ran for the presidency in 2008 and while Obama served two terms as president, said this in a message via Twitter: “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.”

Check out the messages to Sen. McCain.

He earned his hero status the hard way by being shot down during the Vietnam War and by being held captive for more than five years by North Vietnam. He was tortured, beaten to within inches of his life, denied medical treatment for the injuries he suffered when his plane crashed into a lake in downtown Hanoi.

But he persevered. He struggled. He fought back.

As President Obama said, “Cancer doesn’t know what it’s up against.”

John McCain became a national figure the moment he entered Congress and he has served the nation with honor.

We’re pulling for you, senator.