Pathology was performed following McCain's surgery Friday to remove a blood clot, and tests showed the presence of a "primary brain tumor" known as glioblastoma.

The family is now considering treatment options with his Mayo Clinic team of doctors.

The 80-year-old Senator was resting at home following the removal of the blood clot last week. His absence from Congress led Republicans to defer the vote on the repeal and replacement of Obamacare.

His office did not reveal a prognosis.