Chase's adopted father, Rev. Chase, died in 1779 and after that Jeremiah moved fully to Annapolis. That same year he was named a member of Maryland's Executive Council, which functioned as the upper house of the legislature, and he would serve there until 1783, and later from 1785 to 1788. Chase was also Mayor of Annapolis in 1783 and 1784. Those same years he served as a delegate to the Continental Congress, which held sessions for those years in Annapolis. It was there he became a friend of David Howell of Rhode Island.