Why on Earth would a man supposedly motivated so profoundly by a sense of honor lend his good name to a political campaign he must find both morally repulsive and extraordinarily dangerous to the U.S. and its allies around the world?

The answer is remarkably simple: McCain is up for re-election this year and desperately wants to keep his job.

That’s right: The great hero would rather back a patently unacceptable presidential nominee than risk antagonizing a faction of voters who could force him to retire from the Senate, at the age of 80, after five six-year terms.

You can be a paragon of fortitude and courage or you can be a power-hungry party hack. But you can’t be both.

Very few leading Republicans have come through the rise of Donald Trump looking good. But no one has ended up looking worse than John McCain.