Facebook founder Mark Zuckerberg could hold a key to President Obama’s courtship of the youth vote in 2012. Photographer: Tony Avelar/Bloomberg

President Obama will host a town hall event today at Facebook headquarters, a first-of-its-kind event and the latest sign of his renewed courtship of young voters in advance of the 2012 election.

Obama’s decision to trek to the hub of the social networking movement comes on the heels of a heavy youth presence in Obama’s web video announcing his plan to seek a second term that was released a few weeks ago.

“Even though I couldn’t exactly vote at the time, I knew that someday I’d be able to help re-elect him and that’s what I plan on doing,” says a young man identified as “Mike” in the video.

What’s clear is that the Obama political team views young voters a s a fundamental building block to him winning a second term in 2012. The harder question to answer is whether they can they re-create the political magic Obama demonstrated with young people in 2008.

In the wake of the 2008 election, much was made of the power of the youth vote and the ways in which it helped Obama. But there is still widespread misunderstanding about the real impact of young voters.

In 2004, young people — defined as those aged 18-29 — comprised 17 percent of the overall electorate and went for Massachusetts Sen. John Kerry by a nine-point margin.

In 2008, young people were only a slightly higher percentage of the electorate — 18 percent — but Obama won them by 34 points.

But, it wasn’t only Obama’s increased margins among young people that mattered.

In 2004, 120 million people voted, meaning that young people accounted for roughly 20.4 million votes. In 2008, 130 million people cast ballots, with 23.4 million of those cast by 18-29 year olds. (That was the largest turnout of young voters in terms of raw numbers in modern presidential history. The only race that came close was in 1992 when nearly 22 million voters aged 18-29 turned out.)

So, turnout rose by 10 million overall between 2004 and 2008 and three million of that — 30 percent — came among young people.

That simple piece of math explains everything you need to know about why Obama is re-targeting young people so aggressively.

Whether it’s realistic for President Obama and his team to think that they can sustain his 2008 appeal among young people is a point of considerable contention.

The naysayers note that Candidate Obama was able to channel young peoples’ hopes for politics (and society) in a way that President Obama — saddled with the constraints of governing — can’t hope to equal.

“President Obama is going to help us [get the youth vote] because a bunch of people that voted for him last time feel duped, and they aren’t going to sign up again for dupe version two,” former Minnesota governor Tim Pawlenty (R) told the Vanderbilt University newspaper late last month .

Doubters also point out that young people largely checked out of the 2010 midterm elections, comprising just 12 percent of the electorate and watching their overall numbers drop from 23.5 million in 2008 to just 10.8 million in 2010.

Those numbers, they argue, are evidence that Obama’s connection with youth voters amounted to specific moment in time that cannot be re-engineered in 2012. (Turnout in midterm elections, however, is traditionally lower across-the-board than it is in a presidential race.)

Obama allies insist that there remains a plausible case to be made that the youth vote of 2008 is repeatable. The case they make has a symbolic and a demographic element.

On the symbolic level, they insist that young voters retain a genuine connection with Obama and that there is a level of personal investment in him (and what they believe he represents) to think that there will be no lull in excitement within the group heading into 2012.

On the demographic level, there will be eight million people aged 18 to 22 who will vote for the first time in 2012, according to calculations done by Obama’s chief pollster Joel Benenson.

Theoretically, that segment of young voters could more than make up for any dropoff Obama might see in the broader age demographic — particularly if his campaign can win them at the two-to-one rate he did in 2008.

The youth vote was the story of the 2008 election. Obama and his campaign are hoping they can re-tell it again in 2012.