The United States never joined the League. Most historians consider that the League operated much less effectively without U.S. participation than it would have otherwise. However, even while rejecting membership, the Republican presidents of the period . . . agreed with many of its goals. The presidential administrations of Harding, Coolidge, and Hoover worked with League efforts on several issues.. . . However, the coming of World War II once again demonstrated the need for an effective international organization to mediate disputes, and the United States public and the Roosevelt Administration supported and became founding members of the new United Nations. According to this passage, what is one reason the League of Nations failed? The United States failed to join the organization. The United States proved to be a poor leader of the organization. The League did not work diligently enough in forming international relations. The League’s members did not want to prevent war.