WASHINGTON -- The love affair between young voters and President Barack Obama that ignited his candidacy in 2008 and powered him to the White House seems like a distant memory in 2012.

As Election Day approaches, there’s an enthusiasm gap among young voters. New polling from Harvard University’s Institute of Politics found that just 48 percent of voters under age 30 say they’ll definitely vote in November. Four years ago that figure was much higher, at 72 percent, according to a Pew Research Center study at the time.

Absent the national anger over the Iraq War and the sense of history that came from electing the nation’s first African-American president in 2008, young voters can’t seem to find their motivation this time.

“When I talk to young people who aren’t as passionate, who aren’t as enthusiastic about the November election, they talk about it in those terms,” said John Della Volpe, the polling director at Harvard’s politics institute. “2008 was an historical event. They needed to participate, even if politics wasn’t important to them, to say that they were there, that they had a hand in changing the course of America. It’s kind of like our parents, perhaps, saying they were at Woodstock in 1969.”

After securing the Democratic nomination four years ago, Obama won two out of three general election voters ages 18-29. That strong support helped him flip North Carolina, Indiana and Virginia from red to blue.

“Those three states in particular, if not for the margin he ran up in the youth vote, he loses,” Della Volpe said.

But recent polling by the Pew Research Center found that only half of voters under 30 are even certain they’re registered to vote this year. That’s the lowest percentage in 16 years. And just 61 percent are highly engaged in the 2012 elections, compared with 75 percent at the same time in 2008.

With the exception of some recent college campus speaking events, neither Obama nor Republican presidential nominee Mitt Romney has focused much attention on young voters, said Heather Smith, the president of Rock the Vote, a nonpartisan group set up to mobilize the political power of young voters.

“If you register young people so they can vote and you engage them in a conversation on their issues and you ask them to show up, they respond,” she said. “It’s just that there has been a lot less of that leading up to the elections than there was four years ago.”

Part of the problem is that the anti-war and environmental themes that excited young people in 2008 have given way to concerns about Medicare, tax policy and health care, which have never been high priorities for twentysomething voters.

“There’s just so much focus on programs that deal with older citizens,” said Olivia Adams, a 20-year-old sophomore at the College of Charleston in South Carolina. “Even the stuff about the economy is really focused more on people who (have) full-time jobs, not people who are in school who’ll have jobs in the future.”

Campus enthusiasm for the president has been noticeably absent.

“In the last election, students seemed to be the foundation of his campaign,” Adams said. “And this year, honestly, I haven’t seen anything on campus.”