What was the most important reason the US did not ratify the Versailles treaty and didn't join the league of nations?

The most important reason the U.S. did not ratify the Versailles Treaty and join the League of Nations was a strong sentiment of isolationism among the American public and politicians. Many believed that involvement in international organizations could entangle the U.S. in foreign conflicts and undermine its sovereignty. Additionally, there was significant opposition led by figures like Senator Henry Cabot Lodge, who argued for amendments to the treaty that were not accepted, ultimately leading to its rejection. This isolationist stance reflected a desire to focus on domestic issues rather than international commitments.