President Barack Obama, seeking to avert potentially devastating losses for Democrats on Election Day, delivered an impassioned appeal to a cheering throng of college students here Tuesday night to 'keep believing that change is possible,' adding, 'you've got to stick with me, you can't lose heart.' In a 45-minute speech on a packed green in front of the library at the University of Wisconsin-Madison, Obama reached back to the soaring rhetoric that carried him to the White House in 2008. The old-fashioned get-out-the-vote rally, in a brisk wind under gray skies, seemed to energize the president as much as the crowd. 'Change is going to come for this generation -- if we work for it, if we fight for it, if we believe in it!' Obama thundered. 'The biggest mistake we can make is to let disappointment or frustration lead to apathy and indifference.' The high-energy appearance, broadcast to 200 campuses around the country, was designed to stir memories of the final days of Obama's presidential run, when more than 17,000 turned out to see him in this overwhelmingly liberal town. Now, though, with his political clout diminished and voters increasingly dissatisfied with his stewardship of the economy, Obama must pick his audiences carefully. So Democratic strategists have settled on a strategy of trying to recapture the enthusiasm of 2008 by having Obama reach out to young people, especially the first-time voters who turned out in droves for him -- and who may be apathetic, but have not soured on the president as older voters have. The police and Democratic Party organizers said that about 17,000 people crammed into the Library Mall to hear the president, with 9,000 more spilling over into nearby streets. The line to get through metal detectors was more than a mile long, the authorities said. In another throwback to 2008 -- Ben Harper, the singer-songwriter who campaigned for Obama during his presidential run for the White House, served as the warm-up act for the president. With his collar open and his shirt sleeves rolled up, Obama bounded onto the stage, declaring, 'I don't know about you, but I'm fired up!' His talk mixed his standard attack on Republicans -- he said they had driven the economy into 'a ditch' -- with a far more emotional appeal intended to remind young people why they voted for him in the first place, and to urge them to get to the polls to 'finish what we started' in 2008. With just five weeks to go before Election Day, the White House is deploying Obama in a carefully orchestrated mix of events, large and small. His appearance in Madison on Tuesday was the first of four get-out-the-vote rallies Obama is holding in battleground states between now and the election; others are scheduled for Pennsylvania, Ohio and Nevada -- all states, like Wisconsin, where Democrats are in tight races. 