The young socialists' role in the civil rights movement made the Socialist Party more attractive. Harrington, Kahn and Horowitz were officers and staff-persons of the League for Industrial Democracy (LID), which helped to start the New Left Students for a Democratic Society (SDS). The three LID officers clashed with the less experienced activists of SDS, like Tom Hayden, when the latter's Port Huron Statement criticized socialist and liberal opposition to communism and criticized the labor movement while promoting students as agents of social change. LID and SDS split in 1965, when SDS voted to remove from its constitution the "exclusion clause" that prohibited membership by communists. The SDS exclusion clause had barred "advocates of or apologists for" "totalitarianism". The clause's removal effectively invited "disciplined cadre" to attempt to "take over or paralyze" SDS as had occurred to mass organizations in the thirties.