With a great deal of reluctance, I will say what many are thinking. Given the narrow margin in the Senate majority, Sen. John McCain needs to resign. The citizens of Arizona expect elected representatives to show up for duty. Nobody that comes to mind understands "duty" more than John and that is contrary to his actions.
His absence in the SCOTUS confirmations leaves that process in an unnecessary jeopardy. As regretful as it may be, his medical problems do not relieve him from the responsibility to do the job he asked for. At this time, there's plenty of time for the governor to appoint a replacement before the SCOTUS vote reaches the floor of the Senate.
Disclaimer: As submitted to the Arizona Daily Star.