Sen. John McCain, R-Ariz., said Wednesday his ongoing treatment for brain cancer is going fine and told his colleagues on both sides of the aisle that he will be coming back to work after the August recess.

"My treatment is going fine. I'm feeling fine," McCain said during a Facebook Live from his office in Phoenix. "This is a rough disease, let's be very honest about it. That's straightforward. I've always been straightforward.

"I have to beat it. Fortunately, they found it early, and the treatment is going extremely well. I have another week and a half of this kind of treatment that I'm getting, then they will check it out and see if there's anything ... additional that needs to be done."

"Look, my friends, this is a very malicious disease. But I've had other challenges in my time as well," McCain said.

"I don't mean to be repetitious, but to my Democrat friends and some of my Republican friends: I'm coming back," he said with a few chuckles.

The longtime Arizona Republican also remarked he is thankful for all of the well wishes and letters friends have sent him since he announced he was diagnosed with brain cancer in mid-July.

"Even those that want me to die don't want me to die right away, so that's good," McCain said.

McCain is undergoing treatment for glioblastoma, an aggressive form of brain cancer. News of his diagnosis came out just over a week before he voted against a "skinny" repeal of the Affordable Care Act.

On Tuesday, Sen. Ron Johnson, R-Wis., said in an interview McCain's brain tumor might have factored into his vote on the repeal bill. A spokesman for McCain office dismissed the criticism.

"It is bizarre and deeply unfortunate that Senator Johnson would question the judgment of a colleague and friend," a spokesman said in a statement. "Senator McCain has been very open and clear about the reasons for his vote."