On the campus of Ohio State University, the nation’s third-largest college, the battle for young voters often comes down to an uneven fight between campus Republican Niraj Antani and an armada of Obama campaign workers and volunteers.

With a field office just off campus and several paid staffers devoted full time to organizing OSU’s 56,000 students, the Obama campaign and its network of student supporters sets up on the college’s famed Oval nearly every day. The goal is to register students and coax them onto a campaign van for a drive to the county board of elections office to vote early.

That’s allowed, and there's little Antani can do about it. But sometimes Antani spots the campaign talking up students in other outdoor spots without a campus permit. “If that happens,” he said, “I report it.”

Or they’ll solicit students in the student union, off-limits unless the group rents a table. ”I report it every time.”

Once, they e-mailed professors and asked to be allowed to speak in front of their lectures and register students in class. “I was furious,” Antani said. “I talked to the provost about that.”

The campaign says it abides by campus rules — but touts an organization on college campuses that is even more robust than that developed in 2008, when backing Barack Obama was cool. And the reasons for that intense effort are clear.

Polls show that support for President Obama among voters age 18 to 29 remains strong. But they’ve also persistently shown that young voters are less excited and less likely to vote than their elders.

A new study from the Institute of Politics at Harvard University shows Obama leading Mitt Romney by 19 percentage points, 55 to 36. That represents a fall-off from 2008, when the president won young voters by 34 points — 66 percent to 32 percent — over Sen. John McCain (R-Ariz.)

Tight contests in Ohio and elsewhere could hinge on the question of whether the campaign can turn sometimes disengaged young supporters into voters.

A Pew Research Center poll from September found that half as many voters age 18 to 30 said they were closely following political news this year than in 2008, and only 63 percent said they were certain to vote, down from 72 percent four years ago. Only half of adults under 30 said they were certain they were registered.

The results were “startling” said William Galston, a Brookings Institution fellow who has studied youth engagement for years. “All of the signs point in the same direction. And the only question is how far down they go,” he said.

Campaign officials reject the disengagement argument. Last month, they announced that volunteers and workers had registered 10,000 Ohio students in just one week. And they say more than half of newly registered voters in this key battleground state are under the age of 30, numbers that match figures in other swing states.

“How we measure support is what we’re seeing on the ground,” said Clo Ewing, an Obama campaign spokeswoman. “And what we’re seeing is enthusiasm. What we’re seeing is people wanting to get involved.”

To Antani, the Obama campaign’s effort on his campus smacks of desperation. He noted that the campaign said 15,000 attended last week’s Obama rally on campus, only 1,000 more than came out months ago for Obama’s reelection announcement and 20,000 fewer people than attended a 2010 rally Obama held on behalf of then-Ohio Gov. Ted Strickland.

“The key thing to understand is that in 2008, college students and the 18- to 29-year-old bracket believed in then-Sen. Obama. Now, four years later, we’ve seen his record, and they don’t believe in him anymore,” said Antani, a 21-year-old senior from Dayton.

Those working on the campaign’s behalf counter that, with young voters especially, the issues favor Democrats — if they can get distracted young adults to pay attention long enough to hear it.

That’s partly why Obama has held more than 30 campaign events on college campuses this year and the campaign has hosted a series of youth summits, featuring celebrities and top administration officials, on campuses this fall.

“The difference is that in 2008, we had the idea of change. We all believed, we all voted. In 2012, we still believe, but now we’re talking about what President Obama has done for young constituents, such as doubling the amount of money for Pell grants, repealing ‘don’t ask, don’t tell,’ expanding health care, allowing people to stay on their parents’ health care until they’re 26,” said Daniel Traicoff, 21, president of the college Democrats at the University of Cincinnati, another of the state’s massive campuses centered in a key swing county.

“It’s definitely harder. But that doesn’t mean we’re discouraged or disillusioned," he said.

On the last day Ohioans could register to vote last week, Traicoff and other students in Cincinnati were visited by a Democratic National Committee bus that brought actress Lynn Whitfield to campus to give a brief speech about getting fired up to a small gaggle of students.

The “Gotta Vote” bus, which visited 10 Ohio campuses on a trek through swing states, is another part of the college effort, and on this day, it successfully got a vote for Obama from Andrew Brown, 22, a junior from Kentucky who was guided through the process of registering in Ohio instead.

“They told me it the was the last day, and I said, ‘All right. Let’s do this,” Brown said, describing how he then took the Democrats’ van to the Hamilton County Elections Board and cast his first-ever vote in a presidential election. “It was amazing.”

After the bus pulled away, two Obama staffers trekked up to a campus quad and set up their daily table, affixing Obama signs with stickers to the side and laying out buttons for students.

“Have you registered to vote? Today’s the last day!” they told passersby.

“Are you excited to vote?” the campaign’s Ohio youth director, Lora Rae Anderson, asked one young woman as she filled out a voter registration form.

“I am,” she responded.

Afterward, Katie Normand, 19, a sophomore from nearby Madeira, said she was looking forward to casting her first presidential ballot. For Mitt Romney.

Scott Clement contributed to this report.