....Seward introduced three resolutions to the Senate committee. One resolution�not included in Lincoln's proposals�offered that "no amendment shall be made to the Constitution, which will authorize or give to Congress the power to abolish, or interfere within any State, with the domestic institutions thereof, including that of persons held to labor or service by the laws of said State." ....
In his inaugural address, Lincoln noted Congressional approval of the Corwin amendment and stated that he "had no objection to its being made express and irrevocable." ....
By tacitly supporting Corwin's amendment, Lincoln hoped to convince the South that he would not move to abolish slavery and, at the minimum, keep the border states of Maryland, Virginia, Tennessee, Kentucky, and North Carolina from seceding.
Lincoln's March 16, 1861 letters to the governors did not endorse or oppose the proposed thirteenth amendment.
In the context of secession when the South was demanding total surrender, this tepid simulacrum of support (not even an endorsement!) doesn't count.
Lincoln was a lawyer, and quite capable of reserving to himself the thought that at a later date, the Federal Government would be within its powers to compensate the slave states for voluntary manumission and that such action would not constitute interference with domestic institutions.
He was also a politician. As a politician he correctly believed the slaveholders controlled the federal government and that the key to finishing their control was restriction of the expansion of slavery. The rest could and would follow.
It is absolutely true that Lincoln would have done almost anything to prevent civil war. Except give in on restriction of expansion of slavery, because if the South kept control of the Federal government, then slavery really would be preserved forever. His abolitionism, legalistic though it was, kept him from betraying the program he wass elected on.