Speaking at the University of Wisconsin-Madison, the president said young voters "defied convention wisdom" by voting in large numbers in 2008, and "made more difference than all the TV advertising" that goes with a political campaign.
"We need you to stay fired up because there is an election on Nov. 2 that's going to say a lot about the future -- your future and the future of our country," Obama said.
"And I'm back here today because on Nov. 2, we face another test. And the stakes could not be higher."
During a backyard get-together in Albuquerque earlier in the day, Obama discussed the U.S. education system, the economy and his Christianity. Obama said a return of a Republican Congress not only would be bad for the economy, but bad for education, KTSM-TV, El Paso, Texas, reported.
In the GOP's Pledge to America, revealed last week, the party's top economic priority is keeping $700 billion in tax breaks for the wealthy while eliminating education funding, Obama said.
"And the No. 1 issue in terms of us succeeding as a nation is going to be how well we educate and how well we train our kids," Obama said. "Nothing else comes close. One way they (Republicans) would do that is to cut back our education spending by 20 percent and eliminate about 200,000 Head Start programs and reduce student aid to go to college for about 8 million students."
Obama also listed the reasons he became a Christian, telling residents attending the backyard discussion he was "Christian by choice" and "the precepts of Jesus Christ spoke to me in terms of the kind of life that I would want to lead -- being my brother and sister's keeper," The New York Times reported.
"Being my brothers' and sisters' keeper, treating others as they would treat me, and I think also understanding that Jesus Christ dying for my sins spoke to the humility we all have to have as human beings, that we're sinful and we're flawed and we make mistakes and we achieve salvation through the grace of God," Obama said in response to a question.
Obama has been criticized by conservatives who have questioned his Christian faith. The public also is seems confused, with several polls indicating about 18 percent respondents -- wrongly -- think he is a Muslim.
Monday's discussion in New Mexico was the first stop in a four-state campaign swing designed to ramp up enthusiasm among Democrats before the Nov. 2 election.
The conversation was at the home of Andy Cavalier, a disabled retired Marine Corps staff sergeant and his wife Etta, who taught for 36 years in public schools and now is a counselor at an Albuquerque-area high school.
Cavalier's son, Andrew, began crying when he told Obama his father had "sacrificed his body, 17 surgeries," and wasn't getting the medical care needed at the local veterans hospital, the Times said. Obama told the son that he considered government's obligation of caring for veterans is a "sacred trust."