CHICAGO - Those standing near President Barack Obama during his speech at the campaign's final rally in Des Moines, Iowa Monday night noticed a tear streaming down his left cheek as he talked about the early days of his first campaign.

Was the president crying?

Obama campaign adviser David Plouffe, in an interview on CNN, explained the emotion involved in Obama's Iowa speech:

"It was Barack Obama's last campaign event as a candidate. That in and of itself would cause you to reflect. But the fact that it was in Des Moines, you know it was right next to our headquarters in Iowa where we'd all spent so much time.

"You gotta remember, when we launched our race for the presidency, you know, a lot people didn't know who he was, couldn't pronounce his name, didn't give us much of a chance. And I think as the President looked out into that crowd last night, he saw so many people who believed in him and believed in their ability to change the country before anybody else in the country did.