They’ve quit bugging their friends about change, they’re no longer trying to sign up new voters and the knock-on-door day trips now draw only the most hard-core.

One statistic from Rock the Vote, the most aggressive organization behind youthful political participation, illustrates the difference between now and 2008 — just 280,000 young voters signed up in its midterm elections voter drive, a fraction of the 2.5 million who eagerly put their name on voter forms two years ago.

The bottom line: From coast to coast, universities that brim with liberal ideas and idealistic students won’t be sending nearly as many voters to the polls on Nov. 2. And that’s bad news for Democrats.

In Colorado’s Larimer County, which includes the Colorado State University campus, voter registration drives resulted in 20,000 new voters in 2008. This year, only 1,200 came through.

The story is the same in Virginia’s Albemarle County, which includes 90 percent of the dorms at the University of Virginia. In 2008, 6,171 people registered to vote; only 2,714 new registrations came in this year, a number that could be troubling for the reelection efforts of Democratic Rep. Tom Perriello, who won 2008 thanks in large part to students who turned out for Obama.

A couple of hours away at Virginia Tech, Montgomery County recorded 1,441 new voters, far fewer than the 7,402 who sent in forms in 2008.

Such numbers belie claims by the White House and Democrats that the “enthusiasm gap” is closing and the 2008 hope mojo still runs wild. Obama sounded an optimistic note Thursday, predicting to students at the University of Washington, “If everybody who voted in 2008 shows up in 2010, we will win this election.”

And when 26,000 students rallied for Obama at the University of Wisconsin and 35,000 came out for him at Ohio State, the Democratic National Committee’s press shop gleefully circulated the numbers to reporters. But without Obama on the ticket, the more important question is not whether students participate in the kind of mass rallies that defined the 2008 campaign but whether any of that enthusiasm is transferable to congressional candidates or a Democrat running for governor.

“It’s really easy to care about Obama or [John] McCain,” said Tom Stanionis, chief of staff of elections at Yolo County, where the University of California’s Davis campus is located. “It’s a lot harder to care about Meg Whitman versus Jerry Brown. There’s not that charisma factor in that, ‘Oh, my God, this is change-the-world time.’”

Two precincts central to UC-Davis recorded 1,633 votes in the 2008 election, a turnout of more than 60 percent of registered voters. This year, Stanionis said he’d be “astonished” if more than 15 or 20 percent of registered voters at the campus precincts show up.

At the other end of the country, Obama’s presidential candidacy motivated students at the University of New Hampshire to register to vote in record-breaking numbers, sending in many of the 1,600 forms the elections office in Durham got in just the two months before Election Day. But election officials this year finished their voter registration drive with just 150 new student voters.

While they’d be more likely to vote for Obama, out-of-state students are “not going to care about the state election,” said Ann Shump, a Durham election official.

Still, when Obama does campaign in college towns, the impact is significant, according to campaign officials.

After he rallied 15,000 people in Boston for Gov. Deval Patrick last Sunday, more than half of the crowd signed up to volunteer, according to Patrick’s campaign. Alex Goldstein, a spokesman, said he expects “tens of thousands of volunteers” to be knocking on doors on Election Day asking people to vote.

Similarly, Wisconsin Sen. Russ Feingold’s campaign manager, George Aldrich, said that after Obama’s rally in Madison, he saw a “significant increase in our volunteering activity.” When students sign up to volunteer, the campaign sends messages about events to them through e-mail and mobile phone texts, in addition to Facebook, where 29,000 people check in, and Twitter, which alerts 12,000 fans, Aldrich said.

“It underscores that what all these national pundits are saying is absolutely false,” Brad Bouman, a spokesman for Rep. Mary Jo Kilroy, said of the massive crowd at Ohio State. “That there isn’t an enthusiasm gap in central Ohio among students. You have 35,000 students to show up to see Barack Obama. Those are voters. Those are people that are going to be turning out.”

The elections office in Franklin County said that 800,000 people were registered to vote in the midterms, about 45,000 fewer than 2008 levels.

And in some places, such as the county where Penn State is located, students seem to be nearly as committed to voting as they were two years ago. Five precincts in State College reported virtually identical registration numbers from 2008 to 2010. The elections office in Centre County attributed the number to registration drives on campus.

But generally, the ranks have thinned for college Democrats, many of whom said in interviews that they’ve been getting about half as many like-minded students to their meetings and campaign trips as they did in 2008.

Whereas 70 percent of students said they “definitely” planned to vote in 2008, only 35 percent said they’ll do so this year, according to a new Harvard Institute of Politics poll. And even in 2008 there was a fairly large discrepancy between those who said they were going to vote and those who actually did — about 51 percent.

Other polls suggest Obama’s star power has simply diminished among students. What was a 60 percent approval rating in May 2009 is now 44 percent, according to an Associated Press-mtvU survey from late September.

Young people also are marching to the right, identifying with Democrats at just a 9-point margin over Republicans, a Rock the Vote poll from late August reported. In 2008, that margin was twice as big.

Heather Smith, president of Rock the Vote, said the most effective thing Obama did to win the youth vote two years ago was to connect with students at frequent events on their campuses, creating a bond that translated into a unified movement.

“They believed in something together,” she said of the students. “Just because two years has passed doesn’t mean that, all of a sudden, doesn’t mean young people are dramatically different. ... They still need candidates saying, ‘Here’s what I stand for.’”

At least one event in the next week is expected to unite a horde of young people: a rally in Washington hosted by Comedy Central hosts Jon Stewart and Stephen Colbert that’s designed to counter Glenn Beck’s tea party gathering there. But most of the people who show up for their event on the National Mall next Saturday have probably already made plans to vote, according to Tom Jensen, a pollster for the liberal Public Policy Polling group.

“I think it’s mostly folks who would have voted anyway getting together to talk about it,” said Jensen, who said his polling predicts a “massive decline” in the youth vote in the midterms. “If it has any impact, it will be too small to really impact any races or anything like that.”

Obama’s campaign arm, Organizing for America, contends that the students who rallied for Obama in the past weeks have been “encouraging” in showing energy levels similar to the those in the presidential campaign. “Young people in particular feel a strong connection to President Obama,” said Lynda Tran, a spokeswoman for the group.

But even for those committed to voting and working this cycle, the stakes just don’t seem the same.

“If the Democrats hold the House, I don’t think we’re going to see parties in the streets,” said Josh Schneier, secretary of New York University’s College Democrats.

Gabriel Beltrone contributed to this report.