Few things enrage Democrats more than the consistent Republican success in branding Democratic presidential candidates as overprivileged snobs.

And this year, it is happening again.

John McCain may be the son and grandson of admirals, married to a woman with a fortune usually estimated at $100 million.

Yet it is Barack Obama, son of a single mother and grandson of a Kenyan goatherd, who has suffered more damage from the perception that he is arrogant and out of touch. As the Onion headlined: “Portrayal of Obama as Elitist Hailed as Huge Step Forward for African Americans.” Democrats are left to fume in bafflement.

But it’s really no great mystery.

Americans have accepted political leadership from wealthy men from Andrew Jackson to Arnold Schwarzenegger – so long as those men showed that they shared the values and outlook of less wealthy neighbors. But even the merest hint that a candidate regarded himself as somehow culturally or intellectually superior and – whammo! -- that was the end.

Now compare the life stories of the most recent Republican and Democratic presidential and vice presidential candidates.

George H.W. Bush, Dan Quayle, Bob Dole, Jack Kemp, George W. Bush and Dick Cheney were and are all wealthy and successful men. But not one of them owed his wealth and success primarily to his education.

Compare that list to Bill Clinton, Al Gore, Joe Lieberman, John Kerry and John Edwards. For almost all these Democrats, the decisive event of their lives was the letter admitting them to an elite university or law school -- or both.

The contrast between Barack Obama and John McCain is thus familiar and sharp: the scholar and the warrior, the brilliant president of the Harvard Law Review against the gallant prisoner of war.

Also familiar and also stark is the way in which their support is distributed.

The Democratic Party runs strongest where formal educational attainment is widest.

Of the 10 states with the highest proportion of college graduates, Obama will almost certainly win at least seven, with only Virginia, Colorado and New Hampshire offering any hope to McCain. Of the 10 states with the lowest proportion of college graduates, McCain will probably win at least nine, with only Nevada contestable by the Democrat.

The differences between the states are not small. Almost 45 percent of the population of Massachusetts has a university degree, compared to only 14 percent of the population of West Virginia.

Media commentators habitually refuse to acknowledge the implications of this class divide. During the Republican convention, I often drove by a big “Daily Show” billboard that read: “Welcome rich, white oligarchs.” Never mind that surveys of delegates showed that more Democratic than Republican delegates had incomes over $100,000.

However misinterpreted, class will likely prove decisive in determining how voters react to the personal situation of John McCain’s running mate, Alaska Governor Sarah Palin.

Shrum derides Palin’s prolife views as extreme and insists that Hillary Clinton’s women voters will reject them. But Hillary Clinton’s women voters – many of them older and less-educated – may discover that they have much more in common with the personal struggles of a Sarah Palin than they do with the personal triumphs of a Barack Obama.

Since 1990, college-educated America has experienced a sexual counter-revolution. The odds of divorce have steeply declined among college-educated women and out-of-wedlock childbirth remains uncommon.

To these college-educated women, the life story of the Palin family may seem exotic, even disturbing. In college-educated America, children may get pregnant at 17 -- but they do not carry the baby and they do not marry the father. Teen marriage increases the odds of divorce; teen motherhood interferes with education – so educated America frowns on both.

In non-college America, however, it’s still the 1970s. The odds of divorce remain as high as ever, and the rate of out-of-wedlock births among white women has jumped past 25 percent - higher than it was among blacks when Daniel Moynihan diagnosed the crisis of the black family in the 1960s. For many in this group, the Palin story will read like the story of their own families.

With their nomination of Barack Obama, the Democrats have intensified their image as the party of minorities and the upper part of white America. Among whites, Democrats increasingly draw their votes from the educated, from those who have enjoyed success in a destabilizing postmodern culture and global economy.

By choosing Sarah Palin, Republicans, by contrast, have reasserted their identity as the party of white working-class America - of those who worry about cultural and economic threats to their families.

Shrum’s use of terms like “extremism” is not clarifying. Barack Obama, John McCain and now Sarah Palin are all identity politics candidates, who attract and repel for who they are much more than for what they say or do.

— David Frum, a resident fellow at the American Enterprise Institute, is the author of six books, including most recently COMEBACK: Conservatism That Can Win Again. In 2001 and 2002, he served as a speechwriter and special assistant to President George W. Bush. In 2007, he served as senior foreign policy adviser to the Rudy Giuliani presidential campaign. He blogs daily at Frum.NationalReview.com.