Which president was responsible for completing the Louisiana Purchase?

The president that was responsible for completing the Louisiana Purchase was Thomas Jefferson. President Jefferson was concerned that without American control of the port of New Orleans our trade in the western regions could suffer. For example, there was always a threat that when another country controlled the port of New Orleans, this country could cut off the right of Americans to use the port. This would be a potentially devastating blow to western farmers, and it also would have potentially harmful effects on the American economy. When the United States learned that Spain gave control of Louisiana to France, President Jefferson made an offer to buy New Orleans and West Florida for ten million dollars. Napoleon, who was planning a major war in Europe, countered by offering the United States the entire Louisiana Territory for fifteen million dollars. If the United States agreed to this deal, the size of the country would double.
President Jefferson had to be persuaded to make the deal. President Jefferson believed in a strict interpretation of the Constitution. The Constitution didn’t specifically state that the president could buy land. President Jefferson was persuaded to make the deal, and the United States got control of the Louisiana Territory, doubling the size of the country. This deal gave the United States control of the Mississippi River and the port of New Orleans, allowing American farmers and the American people to know that the port of New Orleans would be open for them to trade and to conduct business.
https://www.history.com/topics/westward-expansion/louisiana-purchase

https://www.thoughtco.com/louisiana-purchase-1435017