This year, Obama stoked media excitement that translated into a constant message over the airwaves. The Clinton campaign seemed to ignore this rising class of political interpreters, making no attempt to court them—in fact, infuriating them with a heavily packaged campaign that played into their stereotypes, and mocking the pundits' very purpose by claiming Clinton's victory as "inevitable."

Independent Crossovers.

Independents who vote in Democratic primaries aren't "typical" independents: they're more upscale, and much more politically engaged.

One stubborn barrier to the long-awaited development of a third party in the U.S. has been the reality that self-described independents agree upon almost nothing; a surprising majority of them are downscale, poorly informed and disengaged with politics.

A much smaller group fits the stereotype of the thoughtful, nuanced independent: liberal on social issues, perhaps, but fiscally conservative. These are the ones who might cross over to vote in a Democratic primary.

The one thing most independents do have in common is visceral dislike for the major parties. This is why Obama's message of post-partisanship works so well for them. Independents who vote in primaries tend to be well informed and engaged with the political process. They are predisposed to Obama's central themes, which concern politics itself (activism, unity, reform) and are more concerned with Hillary's campaign tactics than her policy proposals.

This year, the importance of states with open primaries has given the upscale independent voter new leverage; the relatively small electorate gives them large potential impact if they break a particular way. In Virginia and Wisconsin, nearly one in three Democratic primary voters were independents or Republicans; exit polls showed they tilted heavily toward Obama.

Weepy-Eyed Boomers.

Not every Baby Boomer is a nostalgic liberal or ex-Yippie. The "great silent majority" shunned the demonstrations and sit-ins. But the early Boomers for whom late '60s activism was formative are a small but visible group, now at the peak of its influence. Many of them are politicians, journalists, or donors.

For many of them, the wounds of the seminal year of 1968 never healed. Those who chanted "the whole world is watching" saw their hope and excitement dissipate. The promise of that slogan was never fulfilled, and as these children of the '60s start to enter their 60s, their sense of unfinished business takes on urgency.

Now Obama—seemingly Robert F. Kennedy and the Rev. Martin Luther King rolled into one—offers them a two-for-one redemption of 1968's political assassinations and the illusion of picking up where America left off.