After a diverse string of serious roles in pics such as “Coriolanus” and “Rise of the Planet of the Apes,” Scottish thesp Brian Cox is returning to the comedic territory he mined in “Super Troopers,” as he’s in final negotiations to join the cast of Jay Roach’s Warner Bros. comedy “Dog Fight.”Will Ferrell and Zach Galifianakis star as two rival politicians running for a congressional seat in a small North Carolina district election. Cox is in talks to play Galifianakis’ father, a former Senator who has always been distant toward his family — especially his son. Jason Sudeikis, Dylan McDermott, Sarah Baker and Katherine LaNasa co-star in the film, which starts production this month in New Orleans. Political pic will hit theaters Aug. 10, less than 3 months before the 2012 presidential election. Ferrell’s go-to scribe Chris Henchy (“The Other Guys”) wrote the script with Shawn Harwell (HBO’s “Eastbound & Down”). Ferrell and Adam McKay are producing through Gary Sanchez Prods. along with Roach via his Everyman Pictures banner. Galifianakis will also produce. Cox, who has co-starred in several blockbusters including “X2″ and “The Bourne Identity,” may be best known as the man who introduced American auds to Dr. Hannibal Lecter in Michael Mann’s 1986 pic “Manhunter.” Thesp, who next stars as Menenius in Ralph Fiennes’ Shakespeare adaptation “Coriolanus,” also co-stars in Toronto fest winner “Edwin Boyd,” which was recently acquired by IFC Films. Cox is repped by IFA Talent Agency, Insight and attorney Diane Golden.