They had registered in extraordinarily high numbers, studied the candidates and made well-considered choices. Some, like the students at Lincoln University and Bryn Mawr College, were so determined that they boarded buses to reach off-campus polling sites.

Still, they were novices. And for a few, even some whip-smart Ivy Leaguers, all that hopeful momentum slammed to a disconcerting halt when they faced the big white ballot board.

Like the University of Pennsylvania student (whose identity will be withheld to spare him mortification) who stepped into the voting booth in a Wharton lounge, unaware that his backpack had wedged open the blue privacy curtains.

After studying the ballot for several long, flummoxed minutes, he poked out his head and asked the poll worker: "If I'm a Democrat, can I only vote for president?"

Don't judge.

It's been a long campaign, and a long semester. Student groups such as UPenn for Obama have worked since January registering voters, e-mailing, phone-banking, and organizing rallies.

Yesterday, beginning at 7:30 a.m., they staked out the corner of 34th and Walnut, behind police barricades set up next to a toppled stoplight.

Holding a sign urging "Honk for Obama!" Sofia Owen, 22, a Penn senior from Massachusetts majoring in international relations, said - above the noisy response - that Barack Obama had inspired her. "Not only his speeches, which are captivating, but his connection to common people."

Already a veteran political activist, Owen said she had worked on the 2006 campaign of Pennsylvania Democratic U.S. Rep. Patrick Murphy. "He won by half a percentage point, so I know that people like me can make a difference."

Pennsylvania's total registration of 8.3 million voters this year is a record for any primary contest in the state, said Karlo Marcelo, a researcher for CIRCLE, a nonpartisan center at the University of Maryland that tracks youth voting.

While it's not known yet how many newly registered voters are college students, Marcelo said, that group is at least four times more likely to vote than its peers.

Yesterday, many students were sure they could make a difference in this critical race.

"Something that's really special is going on," said Molly Parzen, president of the College Democrats at Bryn Mawr College, who waited 20 minutes to vote at a church in her precinct.

Every half-hour, students arrived there, pouring out of a shuttle van from the campus' nonpartisan "Smart Women Vote" effort.

"It's kind of nice," said freshman Antonia Kerle, "because there is no sort of student apathy."

On most campuses in the state, Democrats outnumber Republicans, according to CIRCLE.

In and around Philadelphia, Obama was the clear favorite. His campaign had mounted an all-out registration drive at Chester County's Lincoln University, one of the nation's oldest historically black universities. As a result, 326 new voters - an 11 percent spike - were registered in Lower Oxford between Jan. 1 and April 6, the highest percentage of new voters in any municipality in the five-county region.

All day, a steady stream of students was transported by bus and by Obama volunteers to the polls, a mile or more away.

Obama "seems to embody the leadership qualities that we need in this country," said Taquia Hearn, 21, of Pittsburgh, who voted for the first time. "I see that it really matters," she said. "Our livelihood is on the line."

At Temple University, Obama's popularity risked backfiring.

"Everyone is so gung-ho for Obama. Almost to an irritable measure," said freshman Adam Maguire. "But I'm still voting for him."

Although smaller, the turnout for Hillary Rodham Clinton was also loud and urgent yesterday.

"I just agree with her policies more," said Christine Einerson, another Temple freshman. "It's also a personal thing for me - she gives a sense of hope to females my age that maybe we can run for president one day."

At Penn, Seth Bluestein, the poll worker at Wharton, said that he began paying attention to politics after the 9/11 attacks. Like his parents, he said, he was voting for Clinton in the primary. But he planned to support John McCain in the general election.

"He won't raise taxes," says Bluestein, 19, who grew up in Northeast Philadelphia and is majoring in political science.

By 1 p.m., he'd helped more than 150 students vote. Dozens, though, had registered so recently that their names were not on the official books. They had to fill out provisional paper ballots.

Most students interviewed said that everyone they knew was voting.

"I know one kid who's not," said Dan Singer, a 20-year-old from Cleveland. "I think he's a nihilist. He's a philosophy major."

The polling place, one of six on the Penn campus, offered newbies a sticker that read "I Just Voted!"

"Yay!" beamed Alyssa Haynes, as she helped herself to one.

A sticker? Really? Like you get after a measles shot at the pediatrician?

"Except better, because it's without the shot!" said Haynes, 18, a first-timer from Kansas. She posed with her roommate for before and after balloting snapshots.

"I'm really excited," she said, and then left to call her mother.

Inquirer staff writers Megan Kelsey, Derrick Nunnally and Nancy Petersen contributed to this article.