Sworn in as a member of City Council in 1968, Cohen became a leader of the independent factions of the City Council, and worked to focus the City Council on previously slighted problems dealing with zoning, public health care, air pollution, governmental ethics, delivery of city services, and race relations. Elected a delegate to the 1968 Democratic National Convention, Cohen supported the Presidential campaigns of Robert F. Kennedy and Eugene McCarthy, and frequently spoke at rallies opposing the War in Vietnam.