DENVER (AP) -- The University of Denver is warning people about scams involving tickets to Wednesday's presidential debate between incumbent Barack Obama and Republican challenger Mitt Romney.

The university, which is hosting the event, says the debate is by invitation only and tickets will not be distributed before Wednesday. The Denver Post (http://bit.ly/PzIThT ) reports tickets handed out to invited university students can't be sold or transferred, and students will have to show identification along with the tickets to enter.