The candidates tell us plenty about their strengths. They're more reticent about their weaknesses (their "buts''), including the less obvious ones.
Every candidate has such an Achilles' heel, a secondary or tertiary liability that can come suddenly to light in a presidential campaign, particularly after the early primary winnowing. It can be a little-known misdeed, personality trait or biographical detail.
Such weaknesses are often hidden in plain sight or obscured by more glaring ones — such as Bridgegate (Chris Christie) or "Oops!" (Rick Perry). Apparent to insiders and cognoscenti, they can be unseen by the average voter, because the election is so far away and the candidates (currently five Democrats, 15 Republicans) are so many.
And sometimes a weakness might be a strength. Is Scott Walker's lack of a college degree a liability or a badge of honor? If Ted Cruz is unpopular with his congressional colleagues, who as a group are unpopular with the public, is that a plus?
DONALD TRUMP
Obvious weakness: Remarks about Mexican immigrants — as well as prominent members of the party he hopes will nominate him, including John McCain, Mitt Romney, George W. Bush, Dick Cheney, Karl Rove, Ronald Reagan, etc.
Other weakness: Hates to shake hands
As Ford O'Connell, a strategist who worked on the 2008 McCain/Palin campaign, notes: "It's got to be a challenge for him to go around barnstorming and kissing babies.''
TED CRUZ
Obvious weakness: Widely despised by Senate colleagues such as McCain, who called Cruz and Rand Paul right-wing "wacko birds''
Other weakness: Trump
In the '16 field, says O'Connell, "Cruz was the fighter who didn't parse his words. Now there's Trump, eating up all the oxygen in that room.''