Obama's task if anything is trickier. His well-documented weakness in the primaries among older and less well-off voters underscores the potential hazard of a campaign built more on aspirational themes than on an image of nuts-and-bolts problem-solving. He lost working-class white voters (those without college degrees) to Clinton by a 31-point margin, 62-31 percent, and white seniors by 63-29 percent. Seniors, in particular, are much less open to change than their younger counterparts.
There also was substantial affinity-group voting in the Democratic primaries. White women went to Clinton by a 60-34 percent margin; African-Americans to Obama by 82-15 percent. White men in many ways were swing voters; overall they went to Clinton by a narrow 48-45 percent, but with enormous state-to-state differences. In Kentucky, Obama lost white men by 70-26 percent, underscoring his particular problem with Southern white men. On the same day, in Oregon, he won them by a 2-1 margin, 66-33 percent.
Overall, Obama won 10 of the 13 states where he won white men, and lost 13 of the 19 states where he lost them (the size of the black population was a factor). And white men are another group in which age and socioeconomic status also played a role, with better-educated and younger white men better for Obama, less-educated and older white men more favorably inclined toward Clinton.
Obama also displayed weakness in other groups, notably Hispanics, losing them by 61-35 percent, and Catholics, by an identical 61-35 percent. White Catholics, along with political independents, are a classic swing voter group in presidential general elections -- a group whose allegiance swings between parties, and one that's big enough to make a difference. And Obama, while well short among white Catholics, won independents by 12 points, 52-40 percent. Both are worth watching closely in the months ahead.
Other groups bear watching as well. Obama did notably well among change-attuned young voters, winning Democrats under age 30 by a 20-point margin, 58-38 percent. But young adults tend to be the least reliable voters; their turnout is always a question. This year they averaged 14 percent of Democratic primary voters, a larger share than in 2000 or 2004 but roughly matching, not exceeding, their 1984-92 levels.
McCain, in his primaries, did notably well among seniors, a more reliable voter group in terms of turnout, winning them by 47-26 percent over Romney. (While McCain's own age is a net negative, its flipside, experience, helps him; watch for him to try to turn the tables by painting Obama as callow.)
Like young adults in the Democratic primaries, African-Americans, though a natural affinity group for Obama, did not increase their turnout overall. They accounted for 19 percent of Democratic primary voters on average, about the same as in years past. (In a notable difference between the parties, blacks accounted for an average of just 2 percent of Republican voters.)
Women are crucial as well; a more Democratic group than men, they accounted for an average 57 percent of Democratic primary voters, vs. just 46 percent of Republican primary voters. (And white men, 47 percent of Republican voters, made up just 28 percent of Democratic voters.)