John Edwards’s campaign seems to have hit a roadblock that could seriously hurt his chances of securing the Democratic nomination. And it has nothing to do with any of his perceived screw-ups that have gotten their share of media attention, including his $400 haircut, his new compound in North Carolina, and his hedge-fund experiences.

There’s no doubt that Edwards made a mistake with the haircut, and that wealthy populist candidates are not easily forgiven for reminding people that they have money. But most candidates on the trail spend a lot on personal appearances — it’s part of the game. As for the value of Edwards’s house, it’s probably comparable to that of the Clintons or a lot of other Democratic candidates, including former Democratic nominees Al Gore and John Kerry. And the hedge fund? Please show me a major candidate whose family hasn’t raked in some cash from a few major investments or consulting. Most are pretty well-off.

No, Edwards’s problem is different, and it’s not even about his politics. It’s about a piece of paper that hangs — or doesn’t hang — on the wall of his office.

Edwards, you see, didn’t go to Harvard or Yale.

In the Democratic landscape of 2007, that doesn’t seem as if it should be a problem. But you’d have to go back to 1984 to find a Democratic nominee (Walter Mondale) who didn’t attend one of those elite universities for either college or graduate school. Before that, a number of Democratic also-rans, including Gary Hart, Paul Tsongas, and Jerry Brown, were also graduates of either Harvard or Yale. And the pattern will continue in 2008 if either Hillary Clinton (Yale Law) or Barack Obama (Harvard Law) wins the nomination.

It’s a trend that hearkens back to the old country, where it’s assumed all leaders belonged to the same debating club at Oxford. Even other Ivy League schools — such as Columbia, Princeton, and Penn — don’t seem to be good enough for the Democrats, much less the Atlantic Coast Conference schools of Clemson, North Carolina State, and the University of North Carolina, at which Edwards received his education.

How the Democrats arrived at this state of affairs tells you a lot about the present state of the party, and why Edwards — a candidate who has been widely praised in everything from The Economist to the Wall Street Journal for setting the substantive agenda for the whole Democratic field; whose campaign appearances have been sharp; who’s been impressive in debates; and whose wife, Elizabeth, has been a formidable asset — is having more than his share of problems.

The Democrats used to be “the party of the people,” and still aspire to that title. But fundraising (particularly now that all serious candidates spurn public funding) and primary politics have been taken over by the well-educated elites for whom Harvard and Yale are the Holy Grails.

These voters and donors all dream of having their kids attend the best Ivies, especially now that the upward path to mobility in America is no longer membership in a labor union — once the backbone of Democratic politics — but is admission to a selective college.

Meanwhile, the elite press is now dominated by former classmates of the candidates. That’s a marked change from a generation or two ago, when the best reporters often didn’t finish college, but instead worked their way up from the police to the political beat.

To these people, Edwards doesn’t pass muster. It’s not that he’s not smart — he clearly has an impressive intellect. It’s much more subtle and insidious: if there’s one unstated lesson these select schools teach you, regardless of how much money your family actually has, it’s how to act like a member of the upper class.

The rules are clear: you should fluently appear to have money, but not appear to make money (which is why an entrepreneur like Michael Bloomberg would never go anywhere in a Democratic primary). And you should never flaunt it. Thus you can own an inherited family palace or a nice vacation house on Nantucket, but building your own ostentatious abode is utterly out of the question. The overriding lesson is to make it all seem effortless — to never seem too ambitious or grasping.

Perhaps Edwards does strive a little too hard; kids who grew up without a lot of money often do. That puts him in the same straits as Jimmy Carter and Lyndon Johnson — two other Southern Democratic politicians who didn’t grow up in a wealthy family and never attended an Ivy. Though both won the presidency — albeit in different political eras — both felt that Northeastern political and journalistic elites destroyed them. They had a point.

In the same vein, Ivy grads know that your intellectual compass must always point toward New England, even if you live somewhere else. The putative cabinets of many Democratic candidates and nominees are chock full of Yale and Harvard profs — which is probably why Cambridge and New Haven have so many wannabe Secretaries of State, but few real ones.