The pundits on Charlie Rose the other night all agreed the candidates are fatigued. Sadly, no one suggested any solutions to this problem (I can see it getting worse) other than one who said Obama ought to take a few days off since he's in the lead.
"What if" scenario: suppose a major candidate in the current or future campaign becomes ill from the rigors of campaigning and is unable to continue. Does that make him/her unfit for the Presidency? For example, if FDR were alive today, it seems that he would not have been able to endure the modern campaign.