WASHINGTON — Once thought to be solidly behind President Barack Obama, younger voters burdened by a bleak employment picture, high gas prices and student loan debt are being aggressively wooed by the Democrat and his likely Republican challenger, Mitt Romney.

In 2008, Obama had a 34-point advantage over Republican Sen. John McCain among voters under age 30. He won about two-thirds of the vote in that age group.

But a new Harvard poll suggests the president may face a harder sales job with younger voters this time around. Obama led Romney by 12 points among those ages 18-24, according to the survey. Among those in the 25-29 age group, Obama held a 23-point advantage.

It’s an opening Republicans hope to exploit by focusing on young people’s disillusionment with the candidate who promised “hope” and “change.”

“I think young voters in this country have to vote for me if they’re really thinking about what’s in the best interest of their country and what’s in their personal best interest,” Romney said Monday in Pennsylvania after announcing his support for an effort Obama is pushing to keep the interest rate on federal student loans from doubling in July. Obama is visiting college campuses in key states this week to rally students around the proposal.

“The president’s policies have led to extraordinary statistics. When you look at 50 percent of kids coming out college today can’t find a job or can’t find a job which is consistent with their skills, how in the world can you be supporting a president that has led to that kind of economy?” Romney said. “I think young people will understand that ours is the party of opportunity and jobs.”

While Republicans don’t anticipate erasing the Democrats’ long-held advantage among the under-30 voter group, they would like to trim it enough to help Romney win the White House.

His aides and advisers have been sharpening a message that assails Obama for an economy that has young people feeling the pinch, too. The Republican National Committee is preparing to launch what it calls the Social Victory Center, which promises to turn the Facebook accounts of supporters into an outreach arm of the party. And Romney’s five telegenic sons, none of them younger than 30, are ready to reprise their roles as campaign surrogates.

Obama has spent the past week casting himself as a defender of the middle class and urging Congress to keep the 3.4 percent student loan interest rate from doubling to 6.8 percent in July. He rallied students during visits Tuesday to college campuses in North Carolina and Colorado, to be followed by a stop in Iowa on Wednesday. Obama carried all three states in 2008, and they are considered among several that could help decide November’s election.

“When a big chunk of every paycheck goes towards loan debt, that’s not just tough on you, that’s not just tough for middle-class families, it’s not just tough on your parents, it’s painful for the economy, because that money is not going to help businesses grow,” Obama said at the University of North Carolina in Chapel Hill. “I mean, think about the sooner you can start buying a house, that’s good for the housing industry. The sooner you can start up that business, that means you’re hiring some folks. That grows the economy.”

“And this is something Michelle and I know about firsthand. I just wanted everybody here to understand this is not … I didn’t just read about this. I didn’t just get some talking points about this. I didn’t just get a policy briefing on this. Michelle and I, we’ve been in your shoes.”

Despite attempts to relate to college audiences by opening up about his and his wife’s experiences with student loans, polling suggests Obama’s job approval rating among these voters has declined. The 75 percent rating he enjoyed in 2009, the year he took office, has dropped to 57 percent, according to Gallup.

That opens the door for Romney and the Republican Party.

Consider North Carolina. Obama won it by fewer than 14,000 votes, making him the first Democrat to carry the state since 1976.

Rick Wiley, the RNC’s political director, said Democrats pulled off that victory by registering “a boatload of college kids.” But fast forward four years and “those college kids are not going to be there. They’re not on campuses anymore. They’re probably under-employed,” he said.

As a result, Democrats and Republicans alike have to court a new class of college-age voters this election cycle, not just in traditional GOP states like North Carolina, Virginia and Indiana that helped push Obama to victory in 2008, but across the country.

“It’s time for a change, and a lot of young voters I’ve seen are losing faith in Obama,” said Maggie Cleary, head of the Washington, D.C., Students for Romney chapter and president of Georgetown University College Republicans. “The biggest challenge we’re going to have is exciting people about Gov. Romney. … They don’t know a lot about him other than that he’s quote, unquote boring.”

That’s one reason why Romney’s advisers and the RNC want to turn the election into a vote against Obama, and not necessarily into a vote for Romney.

Paul Conway, a former chief of staff to former Labor Secretary Elaine Chao, said the “new normal” for college students and 20-somethings is a series of part-time jobs or unpaid internships.

“These are the people who are feeling the impact of the policies,” said Conway, who runs Generation Opportunity, a nonpartisan group created to encourage young people to vote. “They believe Washington is mortgaging their future. They’re watching Washington put them further in to debt.”

The last Republican presidential candidate to win voters under age 30 was Republican George H.W. Bush. He won 52 percent of those voters on his way to defeating Democrat Michael Dukakis in 1988.