A spokesman for Sen. John McCainJohn Sidney McCainRand Paul ‘concerned’ about Kavanaugh Senate Dems tell Trump: Don't meet with Putin one-on-one McConnell: Senate to confirm Kavanaugh by Oct. 1 MORE (R-Ariz.) is criticizing Sen. Ron JohnsonRonald (Ron) Harold JohnsonGOP senator: Harley-Davidson is right to move some production overseas GOP senator: Trump’s policies doing 'permanent damage' GOP senators introduce resolution endorsing ICE MORE's (R-Wis.) remarks suggesting McCain's brain cancer might have been a factor in his vote against ObamaCare repeal.

"It is bizarre and deeply unfortunate that Sen. Johnson would question the judgement of a colleague and friend," a McCain spokesman told NBC.

"Senator McCain has been very open and clear about the reasons for his vote," said the spokesman, who was not identified by name in the NBC report.

McCain was one of three Republican senators to buck their party in voting against the Senate GOP's scaled-down ObamaCare repeal bill.

Johnson earlier on Wednesday told a Chicago radio station that the late hour of the vote and McCain's tumor might have "factored in" to his decision.

“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.