US actress Ellen Burstyn has joined the cast of the original series \"Political Animals,\" USA Network announced Friday. Starring Sigourney Weaver, Ciaran Hinds, Carla Gugino, James Wolk, Sebastian Stan and Brittany Ishibashi, the 6-hour event drama is slated for the cable network\'s summer lineup. Burstyn will play Margaret Barrish, mother to former first lady and current Secretary of State Elaine Barrish Hammond, played by Weaver. Margaret is described in a synopsis as \"a tough Chicago broad and one-time Vegas showgirl.\" Burstyn, 79, starred in \"The Last Picture Show,\" \"The Exorcist,\" \"Alice Doesn\'t Live Here Anymore,\" \"Resurrection\" and \"Requiem for a Dream.\"