Duga, of Coral Springs, Fla., also was charged with larceny and marijuana possession, but those charges were dropped with Friday's plea on the trespassing count, his attorney Al Daniels said. He was sentenced to a year of probation.
Duga was arrested a few hours after staff for John Edwards said Duga crashed a nearby fundraiser for the Democratic presidential hopeful. Duga, who has worked in Democratic politics for years, said he was expected at the event.
Cleland suspended Duga after the arrest and later fired him. Cleland, a Democratic from Georgia, said he hadn't been aware of Duga's criminal record that included drug possession charges.
On Friday, Cleland said: "He obviously needed to turn his life around and he's working hard to do that."