What action did jefferson do that may have been unconstitutional

The correct answer is the Louisiana Purchase.

While the President has the power to negotiate treaties, Jefferson likely got quite a bit ahead of himself when the land was purchased before the consent of the United States Senate.

Furthermore, the Federalists believed that the acquisition of territory itself might be unconstitutional.

richard milhous nixon (january 9, 1913 – april 22, 1994) was the 37th president of the united states, serving from 1969 to 1974, when he became the only president to resign (quit). he is also known for corruption and the watergate scandal which resulted in the public losing trust in him and his resignation.

no one really purchased it themselves, it was all america, they had debates etc.