The office of Sen. John McCain (R-Ariz.) confirmed the former Republican nominee for President has a brain tumor.

Sen. McCain was absent from Congress this past week and underwent surgery to remove a blood clot from above his eye.

Subsequent tissue pathology revealed that a tumor known as glioblastoma was found to be associated with that that blood clot.

According to a statement from the Mayo Clinic, the Senator's doctors say he is recovering "amazingly well" and his underlying health is excellent.

The 80-year-old has represented Arizona in the senate since 1987.

The office of Senator John McCain released the following statement: "Senator McCain appreciates the outpouring of support he has received over the last few days. He is in good spirits as he continues to recover at home with his family in Arizona. He is grateful to the doctors and staff at Mayo Clinic for their outstanding care, and is confident that any future treatment will be effective. Further consultations with Senator McCain's Mayo Clinic care team will indicate when he will return to the United States Senate."