Why was President Andrew Jackson

trying to get the Eastern Tribes removed?

in order to open new land for settlement by citizens of the United States.

Explanation:

With the onset of westward expansion and increased contact with Indian tribes, President Jackson set the tone for his position on Indian affairs in his message to Congress on December 6, 1830. Jackson's message justified the removal policy already established by the Indian Removal Act of May 28, 1830.