In “A Confederacy of Dunces,” which opens at the Huntington Theatre Company Nov. 11, Nick Offerman plays the obnoxious Ignatius J. Reilly, a larger-than-life character with a penchant for belching and farting. “I think I can roll this play right into a GOP candidacy,” the “Parks and Recreation” star deadpanned at a press conference Thursday to promote the show. “My farting is getting good. I start great, it’s the stopping I have to work on.” The play, adapted by Jeffrey Hatcher from John Kennedy Toole’s Pulitzer Prize-winning novel, follows Reilly on a farcical odyssey through New Orleans’s French Quarter. The show is directed by David Esbjornson, who previously directed “Guess Who’s Coming to Dinner” and “All My Sons” at the Huntington. Though Offerman is best known for playing the mustachioed Ron Swanson on the NBC sitcom “Parks and Recreation,” he came of age playing offbeat characters like Reilly on the stage in Chicago. “I arrived at my manhood working in theaters like this, before disappearing into the gutters of popular culture.” Offerman said, adding that, as a “lifelong weirdo and fan of the counterculture,” he holds Toole’s book near and dear. Hatcher acknowledged that it hasn’t been easy adapting the famously picaresque novel, and the script is still being tweaked. There’s certainly a lot of interest in the show. Citing the proverbial “popular demand,’’ the Huntington announced Thursday that “A Confederacy of Dunces’’ has been extended and will now run through Dec. 20, a week longer than originally scheduled. But, remember, Offerman’s character does a lot of belching and farting. “You don’t want to be eighth row center,” joked Esbjornson.