A a bit of a tradition of referring to the President of the U.S. of A. by his initials. JFK and FDR leap immediately to mind.
If John Sidney McCain the 3rd were to win, I can see headlines abbreviating it JSM. Not bad, not exciting, but normal enough.
Now, Barack Hussein Obama, well the media has pretty much put a kibosh on using his middle name because it reminds us his (to use a liberal term) sperm donor is a muslim. That leaves us calling him Barry, nice and informal, and for initials, well just the first and last apparently. Simply out of respect.
That would leave us with B.O. in the oval office if he's elected. Frankly, I think things stink enough in Washington just having him in the Senate...
His leanings may be too extreme for some, but at least there won't be a B.O. problem!