"For all the attention generated by Barack Obama's candidacy, the share of eligible voters who actually cast ballots in November declined for the first time in a dozen years. The reason: Older whites with little interest in backing either Barack Obama or John McCain stayed home. . . . According to census data, 66 percent of whites voted last November, down 1 percentage point from 2004. Blacks increased their turnout by 5 percentage points to 65 percent, nearly matching whites. Hispanics improved turnout by 3 percentage points, and Asians by 3.5 percentage points, each reaching a turnout of nearly 50 percent. In all, minorities made up nearly 1 in 4 voters in 2008, the most diverse electorate ever. By age, voters 18-to-24 were the only group to show a statistically significant increase in turnout, with 49 percent casting ballots, compared with 47 percent in 2004."
In other words, the winner in 2012 will be the candidate who turns on older white voters without turning off younger and minority voters.