Frontrunner meltdown

Now that Hillary has announced her new health plan (the one that's going to work, this time) and solidified her position by appearing on all major Sunday AM talk shows, she has been officially declared front-runner, a position, as she is no doubt aware, that carries with it historic perils.
There have been numerous cases of front-runner meltdown in the history of American presidential politics, but none so dire as that of Republican Thomas Dewey in his campaign to unseat Harry Truman in 1948. Historians often focus on the grand, "give-em-hell" campaign run by Truman--and it was indeed a doozy, a 31,000 mile whistlestop whirlwind with Harry making rousing speeches at every hamlet in America--but, in fact, the race was Dewey's to lose and he lost it.
Before the campaign began, Truman was so roundly disliked in America--post war inflation had set in and the Red Scare had begun--that even members of his own party wondered aloud in editorials "Must it be Truman?" A nasty joke going around the country asked: "I wonder what Truman would do if he were alive?"
On the other hand, Americans had New York Governor Dewey, who had honorably lost in 1944 to Franklin Roosevelt. Dewey was young (forty-six, the first presidential candidate to be born in the 20th century) handsome (well sort of--a comment, famously attributed to everyone from Ethel Barrymore to FDR had it that he resembled "the little man on the wedding cake"), and a crime-buster ala Rudy Giuliani, the candidate who most closely resembles Dewey today. But Dewey suffered terribly from two attributes which cannot afflict a winning presidential candidate: complacency and caution. Since all polls had him way ahead, his advisers told him to sit on his hands and simply avoid saying anything controversial. All the way to the end, Dewey thought he had it won. In fact, he became enraged when Truman announced he was going to send a personal emissary to Stalin to try to mediate with the Soviet leader during the Russian blockade of Berlin that summer. Dewey told reporters: “If Harry Truman would just keep his hands off things for another few weeks! Particularly, if he will keep his hands off foreign policy, about which he knows considerably less than nothing.”
On Election Day, even as Gallup gave the election to Dewey and The Wall Street Journal published an article predicting who Dewey's chief advisers might be and New York Times columnist Stewart Alsop wrung his hands, wondering "how the government can get through the next ten weeks" with Truman as lame-duck president, Dewey got his comeuppance: Harry Truman won by more than three million votes.
The lesson for front-runners: act like you're the last dog in the pack and be sure to keep barking and braying...