Final answer:
Jeffersonian Republicans like Calhoun and Clay supporting the American System is surprising because it contradicts their party's ideals of minimal government and agricultural society by promoting a strong federal influence in the economy.
Step-by-step explanation:
It was surprising that Jeffersonian Republicans like Calhoun and Clay would support the American System because traditionally, the Jeffersonian Republicans were known for their opposition to a strong central government and emphasis on agricultural interests, as well as strict constructionism regarding the Constitution. The American System, supported by Henry Clay, promoted high tariffs, a national bank, and federally funded internal improvements, which would appear to go against the Republican's preference for limited government and rural, agricultural society. Their support of the American System, therefore, seems inconsistent with the core beliefs expressed by early Republican leaders such as Thomas Jefferson and James Madison, who believed in minimal government intervention in economic affairs and strict adherence to the powers granted by the Constitution. The American System was more aligned with Hamiltonian Federalism and economic nationalism, which sought to strengthen the federal government's role in guiding the economy.
The willingness of Republicans like Calhoun and Clay to back the American System also demonstrated the evolving nature of American political parties and the shift in priorities as the country developed economically and socially during the early 19th century. This transformation set the stage for the second party system where Democrats and Whigs represented emerging political and economic differences among the American population.