Republican Sen. Ron Johnson of Wisconsin said Tuesday that he thinks that Sen. John McCain's brain tumor and the early morning hours may have affected the Arizona Republican's no vote on the Senate bill to repeal Obamacare.

McCain voted no on the so-called skinny repeal, explaining in a radio interview last week that he disagreed with the process leading up to the vote and saying he supported repealing Obamacare but with an immediate replacement. McCain returned to the Senate to vote on health care-related legislation after a surgery to remove a blood clot revealed he had brain cancer.

Johnson argued that the brain tumor may have affected McCain's vote.

"We did get a call from Paul (Ryan) and he assured us that skinny repeal was not going to pass the House it would have to go to conference," said the Wisconsin senator on AM560 "Chicago's Morning Answer."

"Again, I'm not gonna speak for John McCain -- he has a brain tumor right now -- that vote occurred at 1:30 in the morning, some of that might have factored in," he continued.

Seemingly shocked, a radio host responded "really?" to Johnson's comments and asked if he really believed McCain's brain tumor might have factored into his judgment.

"Again, I-I-I don't know exactly what -- we really thought -- and again I don't want speak for any senator," Johnson responded. "I really thought he was going to vote yes to send that to conference at 10:30 at night. By about 1, 1:30, he voted no. So you have talk to John in terms what was on his mind."