Answer:
set aside most of his most deeply-held constitutional principles.
Step-by-step explanation:
Jefferson is not exactly ranked among the top best American presidents but he certainly did well in the area of Louisiana purchase from France though it had to change his vision of the Constitution.
Jefferson's perspective ab initio was that the Constitution made no provision for the acquisition of a new territory or incorporating a new territory into the Union as a new
State.
Jefferson had to set aside most of his deeply-held constitutional principles and accept Gallatin’s reasoning concerning the purchase of Louisiana. In Jefferson's idea, the new territory would enter the Union as a matter of “expediency” rather than constitutional principle.