Greg Kinnear will star as the title character in the Powerhouse Theater staging of Stephen Belber’s play “The Power of Duff,” with a cast that includes Maura Tierney, Jennifer Westfeldt and Dominic Fumusa.The developmental production, presented as part of New York Stage and Film and Vassar College’s annual Powerhouse lineup, also will star Desmin Borges (“The Elaborate Entrance of Chad Deity”), Neal Huff, Russell G. Jones (“Ruined”) and Ben Platt. Peter DuBois (“Sons of the Prophet,” “Rapture, Blister, Burn”) helms. Storyline of “Duff,” the latest by Belber (“Tape,” “Match”), centers on a TV news anchor who experiences a spiritual revelation live on the air. Thesps join Chloe Sevigny, onboard for Powerhouse’s upcoming production of Roberto Aguirre-Sacasa’s “Abigail/1702,” in appearing during the 2012 season of the program, presented on the Vassar campus in Poughkeepsie, N.Y. Powerhouse has a strong track record of developing shows that go on to have a future life, including “Sons of the Prophet,” “Seminar,” “February House” and the revival of “On a Clear Day You Can See Forever,” all of which had runs in Gotham during the 2011-12 season. “Duff” will play July 18-29 at Powerhouse. Further casting for the rest of the season, which also will includes concert readings of new tuner “The Fortress of Solitude,” remains to be set.