Until recently, Nate Silver was every Democrat's favorite polling analyst, a statistical oracle hailed for the preternatural accuracy of his Barack Obama victory projections in 2008 and 2012. But lately, the God-like aura that once surrounded Silver has been replaced by liberal dismay over his soothsaying.
The reason for the fall from grace is that Silver now gives Donald Trump a 40-percent chance of winning in November. The widespread skepticism that the bilious billionaire might be elected prompted an exasperated Silver to recently tweet, "Never seen otherwise-smart people in so much denial as they are about Trump's chances. Same mistake as primaries. Brexit."
Hillary Clinton, speaking to a union audience Wednesday, expressed her own form of incredulity when she asked rhetorically, "Why aren't I 50 points ahead?" Plausible answers range from "You're a badly flawed candidate yourself, Hillary" to "The news media, especially cable TV, can't get over its ratings-mad fixation with Trump."
But even the most euphoric Trump triumphalist would admit that the GOP nominee's realistic route to victory depends on a narrow passage along the electoral map. As an illustration, giving the GOP nominee almost all of the swing states (but not Pennsylvania) and one of Maine's four electoral votes would lead to an Electoral College verdict of Trump 270 and Clinton 268.
Such calculations serve as a reminder than the Electoral College consists of flesh-and-blood electors rather than disembodied numbers on a map. And even if the Republicans prevailed on Nov. 8, a handful of electors could cost Trump the White House.
Samuel Miles — a Quaker from Philadelphia and a brigadier general during the Revolutionary War — was the first faithless elector. In 1796, even though he was pledged to Federalist John Adams, Miles cast one of Pennsylvania's electoral votes for Thomas Jefferson, whom he judged less likely to plunge America into a war with France.
According to research by the advocacy group FairVote, 81 other electors in history have pulled a similar trick. In modern times, faithless electors have been motivated by ideology (votes for Barry Goldwater in 1960 and Ronald Reagan in 1980) and idiosyncrasy (an Alabama elector opted for home-town circuit court judge Walter Jones in 1956).
Normally, in a close election, party loyalty trumps any attempt by electors to jigger with the outcome. In fact, it is safe to say that there are few places in America where independent judgment is less prized than in the Electoral College.
But 2016 — in case anyone hasn't noticed — is not a normal election. Already, Baoky Vu, a Republican elector in Georgia, has taken himself off the ballot because he could not bring himself to vote for Trump.
And Politico reported in late August that a Texas GOP elector, Chris Suprun, a Dallas paramedic, also had deep reservations about backing Trump.
I spoke briefly by phone on Thursday with Suprun, who was about to participate in an all-day vigil for the first responders who died on 9/11. "The article is a mischaracterization of my statements," he said. "I got into this with all intentions of supporting the nominee of my party."
If there is already this much public ferment over the sentiments of Republican electors, it is easy to imagine the potential firestorm if, say, Trump ekes out a hairsbreadth victory on Nov. 8. Republican electors would be monitored hourly for any signs of maverick tendencies up until the moment they cast their paper ballots for president and vice president in their respective state capitals in mid-December.
Nothing that we have learned so far in this campaign suggests that President-elect Trump would be magnanimous and reassuring in the first weeks after the election. Maybe he would start talking idly about dropping a nuclear device on ISIS or suddenly announce that Donald Jr. would make a primo justice of the Supreme Court. It doesn't take much imagination to contemplate a wave of buyer's remorse sweeping through the reasonable wing of the Republic Party.
Also, remember that anti-Trump GOP electors would have choices other than making Clinton president. Under the 12th Amendment to the Constitution, if no candidate won a majority in the Electoral College, the House would choose the 45th president among the three highest finishers.
Three? Trump, Clinton and who else?
Going back to my original 270-to-268 electoral vote scenario, all it would take is for one Republican elector to write in a name like, well, Paul Ryan. (Yes, I know that you thought all saving President Ryan scenarios ended with no second ballot at the Cleveland convention).
In that case, the choice would rest with the Republican House voting by individual states. (Currently, the GOP controls 33 delegations, the Democrats 14 and 3 states are evenly split). Maybe Trump would still prevail, but I wouldn't rule out the election of a conservative Republican president who actually knows what the nuclear triad is.
For, in the end, Trump isn't just running against Clinton. He is also running against Samuel Miles and the powerful precedent he set in 1796.
Roll Call columnist Walter Shapiro is a veteran of Politics Daily, USA Today, Time, Newsweek and the Washington Post. His book on his con-man great-uncle was just published: "Hustling Hitler: The Jewish Vaudevillian Who Fooled the Fuhrer." Follow him on Twitter @MrWalterShapiro.