Why did Thomas Jefferson doubted in buying the Louisiana territory?

The power of purchasing land, especially land as vast as the Louisiana Territory, was something that Jefferson wasn't sure was constitutional. Nowhere in the constitution does it say that the federal government has the power to buy land. Jefferson worried that the government was overstepping its boundary.

Also, Jefferson worried that the federal government may become too powerful. He was more in favor of states rights instead of having all of the power located with the central federal government. Despite these viewpoints, Jefferson did a number of acts as president that would tilt him toward federalism as opposed to anti-federalism. One such example would be the Embargo Act of 1807.