Mr. Obama hardly created this moment, with its potent brew of Bush loathing and sweeping generational change. He simply had the vision to tap into it. Running in 2008 rather than waiting four more years was the single smartest political decision he’s made (and, yes, he’s made dumb ones too). The second smartest was to understand and emphasize that subterranean, nearly universal anticipation of change rather than settle for the narrower band of partisan, dyspeptic Bush-bashing. We don’t know yet if he’s the man who can make the moment  and won’t know unless he gets to the White House  but there’s no question that the moment has helped make the man.

For five years boomers have been asking, “Why are the kids not in the streets screaming about the war the way we were?” The simple answer: no draft. But as Morley Winograd and Michael D. Hais show in “Millennial Makeover,” their book about the post-1982 American generation, that energy has been plowed into quieter social activism and grand-scale social networking, often linked on the same Web page. The millennials’ bottom-up digital superstructure was there to be mined, for an amalgam of political organizing, fund-raising and fun, and Mr. Obama’s camp knew how to work it. The part of the press that can’t tell the difference between Facebook and, say, AOL, was too busy salivating over the Clintons’ vintage 1990s roster of fat-cat donors to hear the major earthquake rumbling underground.

The demographic reshaping of the electoral map, though more widely noted, still isn’t fully understood. From Rust Belt Ohio through Tuesday’s primaries, cable bloviators have been fixated on the older, white, working-class vote. Their unspoken (and truly condescending) assumption, lately embraced by Mrs. Clinton, is that these voters are Reagan Democrats, cryogenically frozen since 1980, who come in two flavors: rubes who will be duped by a politician backing a gas-tax pander or racists who are out of Mr. Obama’s reach.

Image Credit... Barry Blitt

Guess what: there are racists in America and, yes, the occasional rubes (even among Obama voters). Some of them may reside in Indiana, which hasn’t voted for a national Democratic ticket since 1964. But there are many more white working-class voters, both Clinton and Obama supporters, who prefer Democratic policies after seven years of G.O.P. failure. And there is little evidence to suggest that there are enough racists of any class in America, let alone in swing states, to determine the results come fall.

As the Times columnist Charles Blow charted last weekend, Mr. Obama’s favorable and unfavorable ratings from white Democrats are both up 5 points since last summer in the Times/CBS poll  a wash despite all the hyperventilating about Mr. Wright and Bittergate. (By contrast, Mrs. Clinton’s favorable rating among black voters fell 36 points while her unfavorable rating rose 17.) Gallup last week found that after the Wright circus Mr. Obama’s white support in a matchup against Mr. McCain is still no worse than John Kerry’s against President Bush in 2004.

But this isn’t 2004, and the fixation on that one demographic in the Clinton-Obama contest has obscured the big picture. The rise in black voters and young voters of all races in Democratic primaries is re-weighting the electorate. Look, for instance, at Ohio, the crucial swing state that Mr. Kerry lost by 119,000 votes four years ago. This year black voters accounted for 18 percent of the state’s Democratic primary voters, up from 14 percent in 2004, an increase of some 230,000 voters out of an overall turnout leap of roughly a million. Voters under 30 (up by some 245,000 voters) accounted for 16 percent, up from 9 in 2004. Those younger Ohio voters even showed up in larger numbers than the perennially reliable over-65 crowd.