Why was Polk upset about the treaty?

President James K. Polk was upset about the Treaty of Guadalupe Hidalgo because he felt it did not go far enough in fulfilling his expansionist goals. Polk had aimed to acquire not only California and New Mexico but also additional territories in the West, and he believed the treaty limited the scope of U.S. territorial expansion. Additionally, he was frustrated by the political opposition and the compromises made during negotiations, which he felt undermined the opportunity for a more comprehensive acquisition of land. Overall, Polk's dissatisfaction stemmed from a desire for greater territorial gain and the belief that the treaty fell short of his ambitions.