Final answer:
The Bonus Army incident adversely affected President Hoover's re-election bid by highlighting perceived insensitivity and mishandling of veterans' demands during the Great Depression, leading to his defeat by Franklin D. Roosevelt in 1932.
Step-by-step explanation:
The Bonus Army incident dramatically undermined President Hoover's popularity, contributing to his defeat in the 1932 presidential election. This event, where World War I veterans were violently dispersed by the army on Hoover's orders, was widely publicized and led to public outcry.
Given the struggles of the Great Depression, the harsh response to the veterans' plea for early bonus payment was seen as emblematic of Hoover's failure to address the economic and social needs of the American people, ultimately boosting Franklin D. Roosevelt's appeal and helping secure his election victory.