AMES, Iowa -- Campaigning under the scorching Iowa sun, President Barack Obama had one eye on the rains pounding the Gulf Coast on Tuesday as he rallied young voters on the first stop of a two-day campus tour.

The storm heading toward Louisiana is threatening a still-recovering New Orleans, which will mark the seven-year anniversary of Hurricane Katrina Wednesday, and the shadow of that devastating storm followed the Obama campaign to Iowa.

Before leaving on the trip, the president made an unscheduled statement, a brief update on his administration's preparations and a warning to residents in the path to not to tempt fate by ignoring evacuation warnings. He kicked off his remarks at Iowa State University with a nod to the looming threat.

"Before I begin, I think it's important to say that our thoughts are with our fellow Americans down on the Gulf," Obama said. "Americans will be there to help folks recovering. When this disaster strikes we're not Democrats or Republicans first -- we are American first."

Obama campaigned as GOP rival Mitt Romney arrived in Tampa for the Republican National Convention, bucking a tradition of lying low during an opponent's party gathering. Campaign spokeswoman Jen Psaki noted recent candidates also had campaigned during the convention. The Obama campaign feels it has no time to waste.

"There are less than 70 days left in the election, until the election, so we know we can't cede a day or a time with voters or a time in an important state," she told reporters.

Obama is seeking to recapture the enthusiasm that gave him an overwhelming advantage with young voters four years ago. The president bested Sen. John McCain with voters under 30 by a 2-to-1 margin. But despite the flood of attention and energy in that campaign, young voter turnout only ticked up by 1 percentage point, to 18 percent of the vote -- evidence of how difficult it is to boost turn out among young voters.

That's Obama's challenge as he heads to three college campuses just as students are settling into a new school year and ready to be registered. Obama addressed a crowd of about 6,000 on a campus green in front of Curtiss Hall, a large neo-classical building. Students wearing the Cyclones' cardinal and gold formed the backdrop.

"It's going to depend on you to close that gap between what America is and what we know America can be," he said, asking students to pitch in the votes and the work that propelled his 2008 campaign. "I'm asking you to believe, I'm asking you to believe in what you can accomplish. We've come too far to turn back now."

Obama's case to young voters has leaned heavily on his support for Pell Grants, overhaul of the federal student aid program and effort to keep low interest for some student loans. In a fuller pitch on Tuesday, he emphasized foreign policy, as well.

"I said we'd end the Iraq war, we did. I said we get bin Laden, we did," Obama said to cheers.

The president also highlighted his health care law and its provision allowing young people to stay on their parents insurance. He again embraced the label "Obamacare" -- "I do care," he said -- and proposed a new name for his rival's health plan.

"Maybe we should call his plan Romney doesn't care," Obama said.

Obama had a stop planned for Colorado State University later Tuesday and another rally at the University of Virginia in Charlottesville on Wednesday.