 In the 1970s, Nader turned his attention to environmental activism, becoming a key leader in the antinuclear power movement, described by one observer as the "titular head of opposition to nuclear energy".The Critical Mass Energy Project was formed by Nader in 1974 as a national anti-nuclear umbrella group, growing to become the largest national anti-nuclear group in the United States, with several hundred local affiliates and an estimated 200,000 supporters.The organization's main efforts were directed at lobbying activities and providing local groups with scientific and other resources to campaign against nuclear power.