United States Senator John McCain has been diagnosed with brain cancer, Reuters reported on Wednesday. The Republican Party member was in the race for the White House in 2008, but was defeated by former US President Barack Obama.

The 80-year-old lawmaker has undergone a surgery to remove a blood clot from above his left eye at the Mayo Clinic in Phoenix, Arizona. He has been recuperating since. Tests after the surgery found that McCain had a brain tumour known as glioblastoma, which is an aggressive type of brain cancer.

Doctors said he was recovering “amazingly well”, and that his health was “excellent”, CNN reported. His family is considering options for treatment, including chemotherapy and radiation.

“It won’t surprise you to learn that in all this, the one of us who is most confident and calm is my father,” his daughter Meghan McCain tweeted on Wednesday. “Cancer may afflict him in many ways, but it will not make him surrender. Nothing ever has.”

After the news broke, Obama called McCain “an American hero”. “Cancer doesn’t know what it’s up against. Give it hell, John,” he said on Twitter.

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