Could it be argued that Jefferson laid the foundations for an imperial US and a powerful federal government?
Because Thomas Jefferson was a Democratic-Republican, you would not think that he would have helped lay a foundation for these things. However, you can certainly argued that he did, indeed, lay the foundations for a powerful central government and an imperial US.
The main argument for this comes from the fact that Jefferson bought the Louisiana Purchase on his own accord as president -- he did not ask permission. He did this even though the Constitution does not give the president permission to do this. By doing this, Jefferson set a precedent that presidents can kind of do whatever they want if it's not clearly unconstitutional. He also gained a huge amount of land for the US and started it on its way to being a huge and imperial country.