This Daily Caller piece answers my question somewhat. It seems to be established that the youth made the difference for President Obama back in 2008.
Obama won 66 percent of the youth vote in 2008, while Republican Sen. John McCain got only 32 percent. Since then, youth enthusiasm for Obama has declined, partly because of high unemployment: More than 50 percent of recent college graduates are unemployed or underemployed.Can the President regain the magic?
Less than 35 percent of the 18- to 29-year-old cohort say they’re likely to vote in 2012, according to an April 26 report by Gallup, which also showed Obama leading Romney in that age group by a 64-29 margin.