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President Barack Obama concentrated his campaign on courting young voters Tuesday, swooping into college campuses as students returned to classes even as he kept a wary eye on the hurricane heading toward the Gulf Coast.

Obama aides see college campuses as fertile ground for registering and recruiting some of the more than 15 million young people who have become eligible to vote since the 2008 election. As Republicans hold their party convention in Florida this week, the president was making a personal appeal to college voters in three university towns: Ames, Iowa; Fort Collins, Colo.; and Charlottesville, Va.

Like the Republicans in Tampa, however, the president has been forced to balance campaign politics with attention to Hurricane Isaac and its path.

Obama aides said that while there were no current plans to change his itinerary, the White House was monitoring the storm and would adjust his schedule if necessary. Isaac was upgraded by forecasters to hurricane status at midday.

Before lifting off from the White House on the Marine One helicopter to begin his two-day trip, Obama warned that the storm could cause significant flooding and other damage and urged residents in the storm's path to heed the advice from local officials.

"Now is not the time to tempt fate, now is not the time to dismiss official warnings," Obama said. "You need to take this seriously."

Obama campaign spokeswoman Jen Psaki told reporters aboard Air Force One that while the president would address storm developments during his travels, the focus of his trip would be to argue for his re-election directly to young voters.

"It's important for him to be out there less than 70 days before the election making the case for why he's a better choice for the American people," she said.

The demands on Obama was made evident as the White House announced that he had signed a disaster declaration for Mississippi in anticipation of Isaac's landfall. The announcement came just moments after Obama landed in Iowa.

The courtship of young voters is an essential part of Obama's campaign plan. His victory four years ago was propelled in part by his overwhelming support among college-aged voters, and polls show him leading Republican rival Mitt Romney with that group in this year's race.

But the president faces an undeniable challenge as he seeks to convince young people that he is the right steward for the economy as they eye a shaky post-graduation job market.

Seeking to overcome that economic uncertainty, Obama's campus staffers and volunteers are touting the president's positions on social issues, like gay rights, that garner significant support among young people. Obama has stressed his effort to freeze the interest rates on new federal student loans, a pitch he personalizes by reminding voters that he and the first lady were once buried under a "mountain" of student loan debt after law school.

They also see a fresh opportunity to court students — and their parents — following Romney's pick of Paul Ryan as his running mate. Democrats say Ryan's budget would cut funding for Pell Grants, the federal need-based program for students, and Obama's campaign is running television advertisements in battleground states trying to link Romney to that plan.

Campaigning last week at Capital University in Ohio, Obama told students that Romney's economic plan "makes one thing clear: He does not think investing in your future is worth it. He doesn't think that's a good investment. I do."

Obama was to speak Tuesday at Iowa State University and Colorado State University. The University of Virginia rejected his campaign's request to hold an event on campus Wednesday, saying it would cause the cancellation or disruption of classes on the second day of the semester. The event was instead being held at an off-campus pavilion in Charlottesville.

Romney's campaign sees an opportunity to cut into the president's support among young people by pushing a three-pronged economic argument focusing on the nation's high unemployment rate, the soaring cost of college and the national debt.

"These kids haven't even entered the workforce and they already owe the government a bill for the debt Obama has rung up," said Joshua Baca, the Romney campaign's national coalitions director.

Obama campaign officials say the start of the new school year is a particularly crucial time to ramp up college registration and make sure those new voters get to the polls. In many of the battleground states, about 50 percent of the college students register to vote on campus after Labor Day, according to the campaign. And even those who are already registered may need to change their address or other personal details after moving to new dorms.

At the University of Dayton, Daniel Rajaiah encourages his fellow Democrats to carry voter registration forms to class, to parties and around campus in case they find someone who hasn't yet registered. Members of the College Democrats set up tables in the middle of campus a few days a week to catch students walking to class or to the cafeteria.

"Our game plan this fall is to hit voter registration very hard," said Rajaiah, who is president of the College Democrats of Ohio.

Obama's campaign said it registered 10,000 voters on college campuses in Ohio last week and signed up 300 new volunteers at colleges in Iowa.

Four years ago, Obama won two-thirds of the vote among 18- to 29-year-olds, compared with just 32 percent for his Republican opponent, Sen. John McCain, according to exit polls.

An Associated Press-GfK poll released last week showed Obama again holding a broad advantage among younger voters, with 54 percent of registered voters under 35 saying they would vote for Obama and 38 percent backing Romney.

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Associated Press News Survey Specialist Dennis Junius contributed to this report.

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