"I was trying to first of all defend John's position," Wisconsin Sen. Ron Johnson tells CNBC.
The Wisconsin Republican drew sharp criticism for saying in a radio interview Tuesday that McCain had "a brain tumor right now. That vote occurred at 1:30 in the morning. Some of that might have factored in."
"I think my comments were completely misconstrued. I was trying to first of all defend John's position. A lot of us were pretty upset about the process, and I was also just being sympathetic with his condition," Johnson said on CNBC's " Squawk Box ." "I've got nothing but a great deal of respect for John McCain."
McCain said he voted against the bill last month because it fell short of the Republican promise to repeal and replace the Affordable Care Act with meaningful reform.
After the radio interview, McCain spokeswoman Julie Tarallo criticized Johnson, saying: "It is bizarre and deeply unfortunate that Senator Johnson would question the judgment of a colleague and friend."
Earlier this week, Johnson said in a statement to CNBC: "I'm disappointed I didn't more eloquently express my sympathy for what Sen. McCain is going through."
Johnson also spoke on health-care reform on Thursday. He said the process isn't over, calling Obamacare "a mess."