Roosevelt watched Wilson try and fail to convince Americans to join the League of Nations at the end of World War I. He learned from this that foreign policy cannot be a matter of partisan politics, and that successful foreign policy has the full support of the people. FDR applied these lessons in World War II by waiting until he had sufficient provocation from the Axis powers before declaring war upon them. Roosevelt obviously supported the Allies wholeheartedly and realized quite early in the conflict that America could not but get involved. However, he appeased himself by providing aid to the British despite several Neutrality Acts passed by Congress, while Americans wallowed in isolationism.

Roosevelt proposed the court-packing plan at the beginning of his second term in office as a means of eliminating the Supreme Court as an obstacle to the New Deal. Motivated by his enormous electoral success in the recent election, he overestimated his own powers and proposed a plan to add a member to the Supreme Court for every member of the court over seventy who had not yet retired, with a maximum of fifteen. As six of the Supreme Court Justices were over seventy, including four of the most conservative, Roosevelt would have had the opportunity to pack the court with staunch New Dealers who would not dispute the constitutionality of his legislation. However, the public was horrified at such an attack on one of the pillars of American democracy. A Democratic Congress vetoed the bill, calling it a "dictator bill." This was the first time that Roosevelt had been turned down by Congress, and it led to a significant decrease in his powers in Washington. Conservatives who realized that the President was no longer invincible began to voice their protests to future New Deal legislation and to the increasing budget deficit.

Roosevelt became President during a unique time in America, when the country faced its most severe economic depression in history. Though he created legislation to address the needs of the people at the time, the idea that endures to this day is that the government is responsible for the people's basic welfare. New Deal legislation such as Social Security, unemployment benefits, labor rights, and bank deposit insurance extended the role that American government played in the lives of each citizen. Because FDR's welfare programs aided those groups in American society who were hit hardest by the Depression, a new voting coalition was created in the election of 1932 and cemented in 1936. The Democratic Party became the party of the African-Americans and of the dispossessed, and the party of the liberals.