There were a number of reasons Federalists opposed the Louisiana Purchase. One can assume some opposed it just because it was Jefferson who made the purchase, out of a kind of reflex. Others had heard wild stories about the land purchased, and thought the purchase a bad bargain. Some thought that the inclusion of Louisiana as the treaty was written would undercut the power of the states by not having each state vote, thus undercutting Federalist power. (Some Federalists in the eastern states specifically feared a shift in power to the west.)
