The self-appointed 19th-century prophet William Miller attracted an intense following when he predicted the end of the world and the arrival of the Second Coming sometime between March 1843 and April 1844. When the appointed time embarrassingly came and went, one of his followers pluckily predicted a new date of Oct. 22, 1844. The Millerites gathered that night to await the blessed event, and instead experienced what became known as "The Great Disappointment."

Barack Obama's supporters and the media (excuse the redundancy) have expected Obama's ascension to presumed Democratic nominee -- accompanied, no doubt, by blazing lights of Unity and trumpet calls of Change -- in New Hampshire, Texas and now Pennsylvania and experienced a "Great Disappointment" each time. They have hoped for a secular political Advent, and instead they have gotten Hillary Clinton -- stolid and barely solvent, and yet with a persistent appeal to Democratic voters.

Pennsylvania was the first post-Pastor Jeremiah Wright and post-"bitter" primary, and Clinton's victory shouldn't be underestimated. She won by nearly 10 points, after getting outspent by roughly 3-to-1 in a state where Obama campaigned for weeks in an effort to finish her off.

Democrats lost the past two presidential elections by nominating candidates who had trouble connecting with down-scale white voters. They are about to do the same, but with their eyes wide open. When Republicans portrayed John Kerry as an out-of-touch elitist, Democrats were shocked: How could this have happened to a candidate they nominated because he was a manly, bomber-jacket-wearing war hero?

With Obama, no surprises will be necessary. He's already been losing blue-collar white voters to ... Hillary Clinton, whose sense of entitlement, nonexistent common touch and dubious credibility throwing back whiskey shots with a beer chaser hardly make her a natural populist. But Obama has transformed her into one.

Obama has won the white vote only in seven states. He lost whites without a college degree even in his native Illinois. Among traditional Democratic voters in Pennsylvania, Clinton racked up numbers as if she had been running against an obscure alderman instead of the most lavishly financed primary candidate in America history, sporting slavish press coverage. She won 70 percent of non-college-educated whites, 59 percent of union members, 69 percent of Catholic voters, and won every income level below $150,000.

The reaction in some liberal precincts was swift -- to come down on Hillary hard. The New York Times all but called on Democratic superdelegates to decide the race for Obama, and chided Clinton for her using Osama bin Laden's image in an ad to illustrate the dangers facing us in the world. How dare she invoke the most public face of the terrorist threat against America! The very brittleness of Obama makes much of liberaldom want to wrap him all the tighter in swaddling clothes.

Cover-ups never work, in scandals or campaigns. Obama's candidacy depends on a kind of make-believe that can't be sustained. How is he going to bring the country together around an orthodox left-wing agenda? How is he going to embody bipartisanship when the significant instances of him practicing it in his legislative career are vanishingly few? How can he heal the nation's divisions when he can't even bridge the Democratic Party's yawning demographic divide?

There nonetheless appears no way out, even if Democrats wanted one. The superdelegates were originally created to exercise their independent judgment if the party were to flock to a flawed candidate in a fit of irrational enthusiasm. But few of them have an appetite for rejecting the candidate with the most pledged delegates, especially when he's an African-American in a party devoted to sensitivity and inclusiveness. Then, there's the alternative. Clinton may have formidable demographic strengths, but they are matched by her stark personal weaknesses.

So Democrats are left to hope against hope that Obama can again become the miraculously unifying figure he seemed in February: "Lord, I believe; help thou my unbelief."