En route to Denver from western Iowa on Air Force One, President Obama made a 15-20 minute phone call to 50 radio disc jockeys, most of them African-Americans in swing states, campaign spokeswoman Jennifer Psaki told reporters.

DJs for Obama, an effort to mobilize young voters to register to vote and turn out to re-elect President Obama, hosted a block party in northwest Philadelphia on Sept., 8th. The event featured four Philadelphia-based disc jockeys spinning music for a crowd of about 100 people.

Obama encouraged the disk jockeys to urge their listeners to register, vote, and vote early if possible -- and to get involved in the election process.

Psaki would not release the names of the radio personalities.

Earlier Wednesday, Obama's campaign sent out an appeal from poet Maya Angelou and released an ad urging supporters to avoid a repeat of the 2000 recount.