There's a certain irony in Hillary Clinton, well known for caution and secrecy, now finding herself on the defensive for an incautious smear of Donald Trump's supporters and simultaneously under fire for failing to disclose a health problem that temporarily knocked her off the campaign trail.
The double whammy to her shaky lead in most of the polls may well be fleeting. But the phenomenon well demonstrates the way unanticipated factors can skewer the most conservative predictions of the outcome of a presidential campaign.
Only four years earlier, Republican presidential nominee Mitt Romney seemed headed to a tight showdown in his bid to deny President Barack Obama a second term. Then, at a supposedly private fund-raiser, Mr. Romney uttered a similarly incautious slap at "the 47 percent of Americans" on federal welfare he said would never vote for him.
Unfortunately for Mr. Romney, an attendee caught the remark on camera, and in unfriendly hands it went "viral." The comment may not have determined the election outcome, but it obliged him to try to explain away the unfortunate implication that he was writing off nearly half of American voters.
Ms. Clinton's comparable dismissive observation was made in televised remarks at a Democratic fund-raiser. She said "half" of Mr. Trump's backers belonged in "a basket of deplorables." She added sarcastic insult to injury by defining them as "racist, sexist, homophobic, xenophobic, Islamophobic — you name it." Worse, she made the remark "in the clear" via television, giving the Trump campaign a gift with a big bow on it.
At a rally in Asheville, N.C., a few nights later, former New York Mayor Rudy Giuliani, one of Mr. Trump's loudest and most visible supporters, chided Ms. Clinton for mentioning "some phobics I've never heard of." Mr. Trump thereupon called some other backers to the stage, crowing: "These are not deplorable people. That I can tell you."
A cardinal rule in politics is never to give your opponent ammunition with which to rally his own troops and followers. The Clinton slur gives the Trump campaign a new argument of party loyalty with which to lure back many longtime Republicans who already are hostile to her but not quite ready up to now to swallow the Trump candidacy.
As for Ms. Clinton's failure to disclose what her doctor subsequently described as pneumonia, that decision unwisely compounded voters' concerns over her penchant for self-protective privacy, which is at the core the email controversy that clings to her.
Consequently, she returns to the campaign trail amid significantly increased skepticism not only about her "likability" but about her trustworthiness as well — the twin political albatrosses she has yet to slay.
With the first televised presidential debate between Ms. Clinton and Mr. Trump only days away, and the campaign already deeply personalized and bitter, a record viewership is more likely than ever. The moderator, Lester Holt of NBC News, a relative newcomer on the national stage, will have his hands full.
Mr. Holt seems a most propitious choice, based on his calm, informed and even-handed performance since replacing the discredited Brian Williams as the NBC nightly anchor. Mr. Holt in a sense will have an opportunity to redeem his network in the wake of the critical roasting suffered by Matt Lauer of NBC's "Today" show recently for not calling Mr. Trump on his false claim to have been against the Iraq war before the 2003 invasion.
The issue is especially pertinent because Ms. Clinton herself as a senator voted to authorize use of military force by President George W. Bush, and Mr. Trump now insists he was right and she was wrong on this critical issue affecting U.S. foreign policy ever since. In any event, the stage is already set for a momentous showdown at Hofstra University on Long Island between these two contentious rivals who share unprecedented public unfavorability in the polls.
In all, the last few days have been a sharp reminder that offhand remarks by presidential candidates, and unanticipated human frailties, can alter the best-laid plans of the most calculating of them.
Jules Witcover is a syndicated columnist and former long-time writer for The Baltimore Sun. His latest book is "The American Vice Presidency: From Irrelevance to Power" (Smithsonian Books). His email is email@example.com.