Senate Republican Ron Johnson of Wisconsin suggested in a radio interview that colleague John McCain’s cancer and the very late hour might have played a role in McCain's dramatic and decisive vote last month against a GOP bill to roll back Obamacare.

Johnson was asked on “Chicago’s Morning Answer” Tuesday about the vote McCain took that effectively ended a Republican push this summer to repeal Obamacare.

“I am not going to speak for John McCain. You know, he has a brain tumor right now. That vote occurred at 1:30 in the morning. Some of that might have factored in,” Johnson said on AM-560 in Chicago in comments first reported Wednesday by CNN. 

“Really?” asked co-host Amy Jacobson, referring to McCain’s surgery for a blood clot and subsequent flight to Washington for the late July Senate health care debate. It was McCain's surgery that revealed the presence of brain cancer. 

“You really think that that played a factor in his judgment call?" she asked Johnson. 

“Again, I don’t know exactly what — we really thought that — again I don’t want to speak for any senator,” Johnson said. “I really thought John was going to vote yes to send that to conference at 10:30 at night. By about 1 or 1:30 (in the morning), he voted no. You’d really have to talk to John about what was on his mind.”

McCain spokeswoman Julie Tarallo responded Wednesday:

“It is bizarre and deeply unfortunate that Senator Johnson would question the judgment of a colleague and friend. Senator McCain has been very open and clear about the reasons for his vote.”

Johnson issued a statement of his own Wednesday afternoon expressing regret over his comments about McCain's vote: 

"I'm disappointed I didn't more eloquently express my sympathy for what Sen. McCain is going through. I have nothing but respect for him and the vote came at the end of a long day for everyone."