Congress clashed with President Johnson, in part, because the framers of the Constitution did not anticipate a civil war or provide for its aftermath. Had Confederate states legally left the Union when they seceded? If so, then their reentry required action by Congress. If not — if even during secession they had retained U.S. statehood — then restoring them might be an administrative matter, best left to the president. Lack of clarity on this fundamental question made for explosive politics.