John McCain

Update at 4:05 p.m. ET

Sen. John McCain, diagnosed with a deadly form of brain cancer just five days ago, returned to applause on the Senate floor Tuesday, where he cast a crucial vote to move forward on repeal of the Affordable Care Act and urged his colleagues to regain their sense of bipartisan cooperation.

However, the longtime Arizona senator, two-time presidential candidate and perhaps America's most famous former prisoner of war, warned that he "will not vote for this bill as it is today," describing it as "a shell."

Doctors use words like "aggressive" and "highly malignant" to describe the type of brain cancer discovered in Arizona Sen. John McCain.

The cancer is a glioblastoma, the Mayo Clinic said in a statement Wednesday. It was diagnosed after doctors surgically removed a blood clot from above McCain's left eye.

Doctors who were not involved in his care say the procedure likely removed much of the tumor as well.

Updated at 12:24 p.m. ET

Beltway denizens heading to work on Thursday were forced to contemplate something inevitable but which no one expected anytime soon: the possibility of a Washington without Sen. John McCain.

McCain, the irascible old living legend. McCain, the Vietnam War hero. McCain, the globe-trotting State Department of one. McCain, the outspoken hawk who championed American troops — and Pentagon spending — and also pilloried the defense contractors he felt let them all down.

The Senate will postpone its consideration of the GOP bill to repeal and replace the Affordable Care Act until Sen. John McCain returns to Washington.

The Republican senator from Arizona is recovering from brain surgery performed Friday to remove a nearly 2-inch blood clot from above his left eye. The surgery was described as a "minimally invasive craniotomy with an eyebrow incision."