One of my most vivid recollections from the Nixon impeachment proceedings was the look on the face of then-Congressman Paul Sarbanes when the roll call reached him on the first Article.  As he voted in the affirmative, Sarbanes' entire demeanor -- his countenance, if you will -- betrayed not partisan delight, self-righteousness, or self-importance; it betrayed the crushing weight of the congressman's appreciation for what his vote -- and the vote of the majority of the House Judiciary Committee -- signified.  
In stark contrast to the smug, gleeful crew that cast their votes for the impeachment of Bill Clinton 25+ years later, Sarbanes seemed almost dazed, not able to believe what was going on, or the role he was playing in the moment.  As he uttered his assent, it was as though he could barely get the word out.  The sheer effort required to say "yes" (or "aye" -- I do not recall which) was almost too much for him.  Yet, he knew all-too-well what was unfolding, and what it meant for the nation.
That was not unlike my impression of John McCain's multiple exchanges with different supporters yesterday.  Even after several rewinds, I doubt -- as some might suggest -- his expression betrays petulance or anger at having to knuckle-under to a handler's instructions to, in effect, "get out there and eat some humble pie."  I think it's more complicated than that.
The knowledge that his quest for the White House is slipping away is hard enough for him to swallow.  The realization that he bears almost sole responsibility for failing is harder, still.  But, what may be even worse is the knowledge that the loss of a political contest pales in comparison to the contributing role played by his abandonment of core principles that defined him for so long.
McCain once told a friend that his experience with the "Keating Five" scandal was worse than the five years he spent in a North Vietnamese prison camp because, in the case of the latter at least, he was able to retain his honor.
Reportedly, George McGovern was at his best in the last three weeks of his campaign for the presidency.  He knew that it was over -- that Nixon and his crew were going to hand him a crushing defeat.  Instead of pouting, stewing or lashing out, McGovern felt liberated by that knowledge.  His acceptance of his fate freed him to say whatever he felt like saying, and simply being himself.

I can't imagine too many people who would willingly trade places with John McCain between now and November 4.  The tangle of emotions he is likely to endure will undoubtedly make him a singularly unpleasant human being for that stretch and, probably, beyond.  Or, not.  It all depends on what he's really made of.