In the hours before his first presidential caucus, Zach Hernandez, 24, sat at his office computer Tuesday in St. Paul, Minn., continually refreshing his page on the Facebook networking site, watching the count of his fellow Obama supporters tick upward. "Zach Hernandez is excited for Minnesota to vote for Obama!" he declared on his personal page.

Even before the votes were counted and the polling data dissected, the campaign of Senator Barack Obama had been riding a surge of interest from young people. Whether that would actually translate into support for his candidacy at the polls was one of the great unknowns of Tuesday's voting.

Interviews across the country on Tuesday produced anecdotal evidence that some younger people did carry their enthusiasm into the polling place. Friends of Chelsea Clinton, Senator Hillary Rodham Clinton's daughter, confided that they were voting for their mother's rival instead. And at Spelman College, a historically black school for women in Atlanta, where Clinton campaign signs competed with photocopied Obama flyers, student after student said she would choose Mr. Obama in Tuesday's voting. Others lobbied friends and parents with clips from boisterous rallies that Mr. Barack has held on and near college campuses.

"It's very much our campaign," said Stephanie Baker, a 19-year old New York University student from Delaware. Since voting started in early January, Mr. Obama has become the Pied Piper of the Democratic race, walking off with a larger chunk of young voters than any recent presidential candidate. By contrast, when 17 to 29 year olds were asked last June in a New York Times/CBS News/MTV poll if they were enthusiastic about any of the candidates running for president, Mr. Obama and Mrs. Clinton tied for first place: 18 percent for him, 17 percent for her.

In voting earlier this year, however, participation by young people did not seem to have increased by an exceptional margin from past presidential primaries; rather, turnout has increased among all age groups.

In the streets around New York University, even the garbage cans wore Obama signs on Tuesday. Washington Square Park, where Mr. Obama addressed over 20,000 jubilant fans on a warm night in September, was gray, silent, and mostly closed for construction.

Inside a nearby Starbucks store, Rachel Barkow, a 36-year-old law professor, said her vote was not only for Mr. Obama but also against the kind of politics she had grown up with - "Whitewater investigations and partisan bickering, a complete us-against-them style of governing," she called it.

Since the terrorist attacks of Sept. 11, 2001, Mrs. Barkow said, she has been waiting for a politician who would seize on the spirit of volunteerism and solidarity the attacks brought. "I have a real desire to be called to do something," she said, and she hears that call in Mr. Obama's speeches.

She hopes Senator John McCain of Arizona wins the Republican nomination, she said, because like Mr. Obama, he strikes her as "emphasizing commonalities among people instead of exploiting their differences."

That was much like the reason that James Wood, 33, a professor at Boston University, gave when explaining that he intended to vote for Senator McCain in the Massachusetts primary. "The fact that he's a maverick is appealing," he said, countering those who have been questioning Mr. McCain's conservative credentials. "He did a very good job in the Senate of not toeing the party line. He could get things accomplished with someone like Ted Kennedy across the aisle. The more ideological candidates have a harder time doing that," Mr. Wood said.

Meanwhile, Mrs. Clinton's young supporters chafed against what they said was becoming an annoying kind of group-think in Mr. Obama's favor. As she trudged through the snow that blanketed the University of Denver campus, where both former President Bill Clinton and Mr. Obama spoke last week, Krishma Parsad, 27, said she was resisting Obama fever. Ms. Parsad, whose home is in Thousand Oaks, Calif., recently cast an absentee vote for Mrs. Clinton.

Tori Spillane, an 18-year-old student at an all-girls Catholic high school in Mendota Heights, Minn., called Mr. Obama's popularity with her peers "frustrating."

"He just picks them up," she said.

Elsewhere, many young people seemed immune from the charms of Mr. Obama or any candidate. On a Manhattan subway car packed with people who turned out for a parade for the New York Giants, not a single member of the young, jersey-wearing crowd reported planning to vote. And at the computer bank of the DePaul University student center in Chicago, the non-voters outnumbered the voters, for a variety of reasons, they said, including failure to register, lack of time and apathy ("I got plenty more years to vote," one student said.)

Many of Mr. Obama's young supporters trained their sights on their elders.

Back at the Starbucks near Washington Square Park, undergraduates were distributing Obama buttons and signs to those older by 20, 30 or even 60 years. "I'm excited that younger people are attracted to Obama," said Tyler Bishop, 86, who shuffled in with his walker to ask for a button.

A few blocks away, Lee Camp, 27, a comedian from Williamsburg, Brooklyn, boasted of having won over his mother. Sure enough, reached by telephone in Richmond, Va., Sydney Fleischer, 61, said her son had swayed her with a flood of emails and links to videos. Because of her son's technological prowess, "he can tell us about some comment that happened 20 minutes ago in Iowa," she said.

However, some have interpreted Mr. Obama's popularity as a protest against baby boomers like Ms. Fleischer; after all, in early voting contests, Mr. Obama's support was strongest among those age 45 and younger.

"He's not my parents' age, so that's kind of appealing to me," said Isaac Sernoffsky, 25, of Chicago. Baby boomers "have had many chances to change the world, and they've just screwed it up and changed their minds so many times."

"I love my parents, obviously," he added.