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.