President Obama won 66 percent of the 18–29 vote in 2008. But young voters may not embrace the reality of Obama in 2012 as they did the promise in 2008.

A new Gallup poll finds that Obama still gets 64 percent of the youth vote, but only 56 percent of young people say they definitely intend to vote — compared with more than 80 percent in other age groups. And a new poll from Harvard University’s Institute of Politics has even worse news: Among college-age youth, only 50 percent approve of Obama’s performance, only 39 percent approve of his handling of the economy, and only 41 percent say they’ll vote for him, to 29 percent for Mitt Romney.

Obama has been working hard to fire up his youth base. He’s stumped the country promising to keep interest rates low on student loans, and every voter likes free money. And then perhaps more importantly, he re-established his cool by endorsing gay marriage. Hope and change are back. For many young voters, this reconnected them to the hip young Obama of 2008.

Nevertheless, he’s carrying a lot more baggage than he was four years ago, when every voter could see what he or she wanted in the largely unknown young senator. Take a look at a few issues that may disillusion young voters.

War. The single issue most identified with Barack Obama in 2008 was his opposition to the war in Iraq. He said repeatedly, “I opposed this war in 2002. I will bring this war to an end in 2009. It is time to bring our troops home.” It took him two more years, and we’re leaving 17,000 Americans at the world’s largest embassy compound, but combat operations have ended in Iraq.

Meanwhile, the longest war in U.S. history drags on in Afghanistan. Even President Obama’s scheduled drawdown would leave twice as many troops there as when he took office. He also launched military action in Libya without congressional authorization, and there are U.S. military actions underway or threatened in Yemen, Syria, Iran, and central Africa. All that doesn’t seem like what young people expected when candidate Obama boasted of his “consistent and constant” opposition to George W. Bush’s wars.

The war on drugs. In 2008 Obama was more candid about his own past drug use than any previous president. And he promised not to use federal agencies to override state laws on medical marijuana. But early in 2009, at an online town hall, President Obama mocked the questioners who asked him if we might stop arresting a million pot smokers every year. He’s reversed his promises on medical marijuana, and he’s sending commando-style squads of drug agents into Central America and the Caribbean to prosecute the drug war. Not what young people were hoping for from a new-generation president.

Jobs. President Obama’s policies have produced the slowest economic recovery in history. An analysis from the Center for Labor Market Studies at Northeastern University found that more than half of young college graduates were unemployed or underemployed last year. Graduating in a bad economy can reduce your income for a decade or more. College students who enthusiastically joined the Obama campaign in 2008 are now wondering what became of the change they hoped for.

Debt. And finally, perhaps the longest-term impact President Obama will have on today’s young people. The national debt has increased by $5 trillion, about 50 percent, during Obama’s 3–1/2 years in office. As a percentage of GDP, it’s the highest since World War II. The average amount of student loan debt is $25,000, but each American owes about $45,000 for the national debt.

Worse, the unfunded liabilities of Social Security, Medicare and other entitlements programs are estimated anywhere from $62 trillion to twice that much. That amounts to $500,000 to as much as a million dollars for every American household. The promises that government has made are unsustainable, and it’s today’s young workers who will end up holding the bag when the money runs out.

Young voters still aren’t very keen on Mitt Romney or the Republican Party. But their enthusiasm for President Obama and his policies is likely to be much more muted than in 2008. That Harvard survey showed that only 20 percent of 18- to 29-year-olds think “Government spending is an effective way to increase economic growth,” which should make them pretty skeptical toward the Democrats. With the wars slogging on, the economy not producing jobs, the president mocking the idea of drug legalization and debt piling up, Obama has a big rehab job facing him with young voters.