The Harvard Institute of Politics released a poll of young voters yesterday. On the surface it seems like good news for Obama and holds few surprises. Obama has the slacker vote firmly sewn up with young voters supporting him by a 55-36 margin over Mitt Romney.

America’s 18-29 year-olds trust President Obama more than Governor Romney on key issues
When America’s 18-29 year-olds were asked which presidential candidate they trust more to handle a number of top issues, late September IOP polling shows President Obama favored over Governor Romney on health care (+23), foreign policy (+23), to be the Commander-in-Chief of the military (+22), immigration reform (+20) – and the economy (+19 percentage points). Obama was also trusted more to handle “issues of concern to someone your age” (+31) and “issues of concern to women (+33).

In addition, six-in-ten Millennials (62%) said the statement: “the problems President Barack Obama inherited are so complex it takes more than four years to do the job” came closer to their own view, while only a third (33%) said the same about the statement: “despite his best efforts, President Obama has failed.

But, as the Washington Post notes, this is not quite as good as it seems. The youth vote was a huge factor, or so we are told, in Obama’s success in 2008. The article notes that contrary to mythology, the youth vote in 2008 was basically the same as it had been in the past but the difference was in Obama’s margin of victory.

Political observers and even casual followers of politics have likely found themselves talking about the importance of the “youth vote” at some point or another. To understand the clout young voters wield in the electorate, it’s worth looking at what did and did not change in 2008, compared to previous elections.

As The Fix boss noted earlier this year, the youth vote — which refers to voters 18 to 29 —  is often misunderstood. Take 2008, when talk about the strength of Obama’s support from young voters was everywhere. Here’s what happened that year: Obama won young voters by a wider margin than any Democratic nominee in the last three decades.

What didn’t happen is often overlooked. Young voters’ share of the electorate barely changed in 2008 — it ticked up a single percentage point (to 18 percent) from where it stood during the three previous elections. In other words, from 1996-2004, fewer than one-in-five people casting presidential ballots were 18 to 29. In 2008, that was still true.

Where Obama won significantly was boosting his take of that vote to a 34 point margin, 66-32, over John McCain. But, following the adage that “you can’t fool all the people all the time”, Obama support among young voters is cratering.

That said, there are signs that young voter turnout may not even be where it was in 2008 and the previous three presidential elections. In combined Washington Post-ABC News polls in September and October, 67 percent of registered voters under 30 said they are absolutely certain they will vote. During the same period in 2008, that number was 80 percent.

A recent Pew Research Center study indicated that that just 63 percent of young registered voters said they definitely planned to vote — a drop from 72 percent four years ago. The Pew survey showed that only about half of adults under 30 said they are absolutely certain they are registered to vote — also a drop from 2008.

But that isn’t the real bad news for Obama, young Obama voters are just not excited.

Put simply, young Romney supporters are less common than young Obama supporters, but they appear to be more resolute. Sixty-five percent of young voters supporting Romney say they will definitely vote this fall, compared to 55 percent of young Obama supporters.

If this is correct, then the actual advantage Obama has in the youth vote is much closer to seven points. If Obama is at parity with women and only takes the youth vote by seven it is difficult to see how he wins.