Abed, a republican candidate, has been mayor of Escondido since 2010.
Abed has called for his opponent Roberts to resign after two staffers filed claims with the county alleging he misused taxpayer money and had an inappropriate relationship with a staffer.
"It's critical to have a fiscally conservative supervisor," Abed said. "I can tell you what I`ve seen is enough to make me run for that seat because San Diego County deserves leadership with integrity and honesty."
Gary Gardner, spokesman for Roberts, says the former staffer's claims are bogus and has asked voters to look past "political rhetoric" and focus on the record.
"We don`t know of an official investigation, that's speculation,'' said Gardner. "[Dave] has been a good supervisor, he works well with his staff. He made some bad hires. It didn't work out."
Roberts was the first Democrat to be elected to the board in 20 years.
The District 3 Supervisor represents communities including Solana Beach, Del Mar, Mira Mesa, Escondido and more.