When Linc refuses to sit with Tod and Midge, Tod tells him that even "President Lincoln sat down to sign the 13th Amendment." This is wrong for two reasons. First, Lincoln was already dead from assassination when the 13th Amendment was completed. It's likely Tod was really thinking about the Emancipation Proclamation, since they both deal with the abolition of slavery. The second reason Tod was wrong is the fact Presidents have nothing to do with Constitutional Amendments. Unlike ordinary Congressional acts, a constitutional amendment does not require presidential signature for passage. Once a proposed amendment is passed by the Congress it goes out directly to be ratified by the states. This prevents the President from blocking a proposed Amendment.