Final answer:
Lewis Cass and other proponents supported the Indian Removal due to their belief that Native American sovereignty within states was incompatible with state sovereignty, despite the Cherokee's extensive acculturation. Economic interests in the fertile lands and discovered gold on Cherokee territory fueled the push for their removal, leading to the Trail of Tears.
Step-by-step explanation:
According to Lewis Cass, the Cherokees, despite having acculturated significantly to white American society, were unable to live with success alongside a 'civilized community.' Cass, along with other proponents of Indian removal, believed that the sovereign existence of Native American groups within state boundaries was an obstacle to state sovereignty. The Cherokee had adopted an American-style government, converted to Christianity, become literate, published a newspaper called The Cherokee Phoenix, and engaged in American-style agriculture and business. Even with these significant efforts at acculturation, the Cherokee and other tribes of the Southeast were still pushed for removal to open up their fertile lands for white settlers' economic interests, especially after the discovery of gold on Cherokee lands. The policy culminated in the enforcement of the Indian Removal Act and the tragic event known as the Trail of Tears.