A serious plot to kill Abraham Lincoln may or may not have existed. (Four years later an equally frothy situation did in fact produce a John Wilkes Booth, completed with a loaded derringer; it would develop eventually that in a time of civil war the most grotesque improbabilities can be built on ugly facts.) Washington had been full of ominous rumors all winter. The War Department had gone to great lengths to build up a thoroughly loyal home guard in the District of Columbia to prevent a seizure of power by secessionist sympathizers, and Winfield Scott had remarked that the general tension was such that "a dog-fight might cause the gutters of the capital to run with blood." Just before Lincoln left Springfield, a citizen visited the old general to ask whether precautions had been taken to make sure that Congress could formally count the electoral vote; it was being rumored that a mob would rise and prevent it, thus (presumably) making it impossible for Lincoln to take office.
"I supposed I had suppressed that infamy," said General Scott. "Has it been resuscitated? I have said that any man who attempted by force or unparliamentary disorder to obstruct or interfere with the lawful count of the electoral vote for President and Vice-President of the United States should be lashed to the muzzle of a twelve-pounder and fired out of a window of the Capitol. I would manure the hulls of Arlington with the fragments of his body, were he a Senator or chief magistrate of my native state!" Subsiding a little, the general added: "While I command the army there will be no revolution in Washington."
L.E. Chittenden, Recollections of President Lincoln and his Administration, New York, 1891. p. 37-39
in
The Coming Fury: Volume One in the American Civil War Trilogy by Bruce Catton, 1961. p. 224 (I think?)