US intervention in the war, as well as the Wilson administration itself, became deeply unpopular. This was reflected in the U.S. Senate's rejection of the Versailles Treaty and membership in the League of Nations. In the interwar era, a consensus arose that US intervention had been a mistake, and the Congress passed laws in an attempt to preserve U.S. neutrality in any future conflict. Polls taken in 1937 and the opening months of World War II established that nearly 60% regarded intervention in WWI as a mistake, with only 28% opposing that view. But, in the period between the fall of France and the attack on Pearl Harbor, public opinion changed dramatically and, for the first time, a narrow plurality rejected the idea that the war had been a mistake.