President Truman opted not to run for reelection for a second time primarily because

By 1952, attention had shifted from Truman’s domestic agenda to foreign policy, especially the Korean War and Cold War tensions. The war was costly and unpopular, and Truman faced criticism over his handling of it. Those pressures helped lead him to decide not to seek another term, so the best choice is “the national focus shifted from domestic affairs to foreign policy concerns.”

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