Final answer:
The goal NOT sought by the Populist Party was expanding the power of big business, as it aimed to support the interests of farmers and the working class, not large corporations.
Step-by-step explanation:
The main answer to the question of which goal was NOT sought by the Populist Party is expanding the power of big business. The Populist Party, formed in the 1890s, aimed to represent the interests of farmers and working class people, not big businesses. Promoting the rights of laborers, implementing a graduated income tax, and increasing government regulation of railroads were all among their objectives. The party was fundamentally opposed to the interests of big business and sought reforms to assist the workers and farmers against the powerful corporate interests of the time. An example of their reformative spirit can be seen in the direct election of U.S. senators, which the Populists supported and which later became law with the Seventeenth Amendment.