Why was the Louisiana Purchase a bit of an embarrassment for Jefferson

Answer;

Louisiana Purchase a bit of an embarrassment for Jefferson because his decision to buy the land went against his own belief to strictly follow the words of the Constitution.

Explanation;

The reason this deal was an embarrassment to Thomas Jefferson is that it contradicted his political ideologies and campaign promises. He was a Constructionist, which means that he believed in a strict interpretation of the Constitution. In his campaign, he promised a small government, no national debt, and limited use of executive privilege. When Jefferson made the deal for the Louisiana purchase, it was believed by some to be unconstitutional because he failed to obtain congressional approval before making the purchase.

One of the reasons why the Louisiana Purchase was a bit of an embarrassment for Jefferson was because it called for an unprecedented and very large exercise of executive power to make the purchase, and Jefferson was largely opposed to such "big government" moves.