Senator McCain will receive radiation and chemotherapy treatment at the Phoenix Mayo Clinic.
McCain made worldwide headlines after his pivotal no vote on the so-called skinny repeal of Obamacare sunk the measure for good. He was diagnosed with a primary glioblastoma this month, after undergoing a craniotomy to remove a blood clot above his left eye. "I like people who weren't captured".
McCain had hoped the Senate could take up the National Defense Authorization Act before he had to leave Washington again.
McCain was also in Washington Tuesday in an effort to steer the annual Defense spending bill through Congress pushing for a big increase in the Pentagon budget.
"Sen. Rand Paul requested two bipartisan amendments, one on ending indefinite detention and one on AUMFs", Paul's spokesman, Sergio Gor, said in a statement. During that time, Senator McCain will maintain a work schedule. "He looks forward to working with leadership and the committee to get this done soon", said Sergio Gor, a spokesman for Paul, when asked about the objection.