Final answer:
The President justified the national bank based on economic necessity and Hamilton's broad interpretation of the Constitution, despite opposition that centered on the 10th Amendment and favoritism concerns.
Step-by-step explanation:
The president justified approving the national bank based on Alexander Hamilton's arguments for a broad construction of the Constitution. Hamilton, as the Secretary of Treasury, believed that the bank was vital to the country's economic interests and made a compelling case that it was both necessary and proper under the 'necessary and proper' clause (Article I, Section 8). This led to the establishment of the First Bank of the United States. Meanwhile, President James Madison approved the Second Bank of the United States after the War of 1812 highlighted the necessity of supporting economic development, which significantly outweighed prior constitutional objections.
Although Washington was initially perplexed by the constitutional issue, Hamilton's argument about the bank's necessity and Madison's subsequent actions demonstrate how the economic benefits and stability provided by the bank influenced its approval. The bank's stable currency system was a significant factor in gaining support, despite opposition from figures such as Thomas Jefferson and the later challenge from President Andrew Jackson who ultimately defeated the renewal of the Second Bank's charter during the 'Bank War'.