The best theory that describes the northern anti-slavery position is the one that talks about that the congress has the roght/duty to prohibit slavery in its jurisdiction.
Hope this helps.
They were chosen by the state legislatures
President Franklin Delano Roosevelt (FDR)
The decision to erect a memorial to Thomas Jefferson was passed by Congress in 1934. Controversy occurred when the Tidal Basin was chosen in 1937 as the site for the memorial. The Tidal Basin is a reservoir between the Potomac River and the Washington Channel. Putting the memorial there required the removal of flowering cherry trees, and there was some objection to that. There was some controversy also over the design of the memorial itself. But FDR, who had been the one who had, in 1934, suggested to the Commission of Fine Arts that a memorial to Jefferson be built, approved the pantheon design for the memorial and gave the project permission to proceed.