A nascent conservative campaign to turn out young voters is gaining steam in the homestretch to Election Day as Republicans capitalize on what some argue is a key opening for GOP presidential nominee Mitt Romney.

President Barack Obama decisively swept the youth vote in 2008, capturing 66 percent of voters ages 18 to 29, compared with just 31 percent who voted for Sen. John McCain (R-Ariz.) But that was then, according to polls that suggest young voters are less engaged, less certain they have registered and less enthused about Obama than they were four years ago.

Conservative youth organizations, some backed by major GOP donors, are airing Web and TV ads, organizing campus rallies and using social networking to woo young voters. Their rallying cry is disproportionately high youth unemployment, rising college costs and student loan debt and the uptick in young college graduates living with their parents.

“Romney has a historic opportunity to attract young people,” said Ron Meyer, a spokesman for American Majority Action, a conservative nonprofit that this month launched a new initiative dubbed Students Against Barack Obama. The group’s name satirizes the Obama camp’s sophisticated Students for Barack Obama program, which operates affiliates on college campuses all over the country.

“You’ve got young people who are really disappointed, who are frustrated,” said Kristen Soltis, communications adviser to Crossroads Generation, a super PAC launched in May to mobilize young GOP voters. “That’s really opened an opportunity for Republicans to reach young people.”

Launched with seed money from GOP heavy hitters such as the super PAC American Crossroads and the Republican State Leadership Committee, Crossroads Generation will spend $1 million or more in this cycle, Soltis said.

The group will unveil a $50,000 TV ad campaign in targeted states this month, broadcasting its ad “The Poster,” which drew more than 200,000 Web viewers during the Republican National Convention. The ad culminates with a college graduate peeling his Obama poster off the wall of the childhood bedroom where he still lives.

In a similar vein, the College Republican National Committee has launched a website touting youth debt and unemployment statistics dubbed OOMPH! (Out of My Parents’ House).

Other groups targeting young voters include Generation Opportunity, a nonprofit that bills itself as nonpartisan but that is run and staffed by Republicans, whose conservative talking points include small government and deregulation. Young Americans for Liberty, a youth-oriented nonprofit with a libertarian streak, lists big-spending GOP allies such as Americans for Prosperity, Americans for Tax Reform and FreedomWorks as its “strategic partners.”

“These organized efforts are much more impressive than they were in ’08 on the Republican side,” said Peter Levine, director of the Center for Information & Research on Civic Learning and Engagement.

For his part, Obama officially launched his re-election with two college campus rallies in May and has made reaching young voters a centerpiece of his campaign.

Obama has visited campuses more than 130 times during his tenure as president, by Students Against Barack Obama’s count. His favorable rating among young voters remains 16 points higher than Romney’s — 58 percent compared with 42 percent for Romney, according to an October survey the Pew Research Center for the People and the Press.

But that’s a 17-point smaller advantage than Obama enjoyed in September, according to Pew. Young voters who overwhelmingly backed Obama in 2008 are returning to a more historically typical pattern in 2012 of voting along similar lines as their elders, Levine said.

The tea party and Occupy movements, along with the campus popularity of presidential candidates such as Rep. Ron Paul (Texas), who sought the GOP nomination without success, and Green Party nominee Jill Stein, are further fracturing the youth vote, he added.

“The gap is more normal,” Levine said. “Obama enthusiasm is probably somewhat down; Romney enthusiasm is probably better than McCain enthusiasm was.”

Such shifts will not necessarily benefit Romney, however. While the percentage of young voters following campaign news very closely is down compared with 2008, according to a September Pew Research Center survey, the drop was even more pronounced among young voters backing the GOP nominee.

Ironically, GOP-backed restrictions on voter registration and ballot access in more than a dozen states may affect the Republican youth vote drive. Student voters tend to lack the photo IDs that are now required to vote in many states, experts say.

Voter registration groups such as the League of Women Voters and Rock the Vote, moreover, have been so busy challenging the new restrictions in court that they’ve had fewer resources to concentrate on actually registering voters.

“We’re out doing our work and fighting these laws at the same time,” Rock the Vote President Heather Smith said. Despite a string of court victories, such groups are now scrambling to clear up widespread confusion over the rules.

Even a small shift in youth voting patterns could make a big difference. About 46 million young Americans are eligible to vote, according to CIRCLE. If 51 percent of them turn out, as was the case in 2008, that’s more than 23 million voters. GOP college student Sam Bain, chairman of the Ohio College Republican Federation, said, “We don’t even have to win the majority of the youth vote to win the election.”