With the impending adjournment of Congress, Lincoln invited members from the Border States for discussion. His logic was about gradually losing what they would be losing anyway, and being paid for it. Eventually eight of the men agreed, while twenty did not.

7/12/1862 ...believing that you [congressmen] of the border states hold more power for good than any other. I...appeal to you; if you all had voted for the resolution of the gradual emancipation... last March, the war would now be substantially ended. Let the states which are in rebellion see, definitely and certainly, that, in no event, will the states you represent ever join their proposed Confederacy...But you cannot divest them of their hope...as long as you show a determination to perpetuate the institution [of slavery] within your own states...

It [slavery] will be gone, and you will have nothing valuable in lieu of it. Much of its value is gone already. How much better for you, and for your people, to take the step which, at once, shortens the war, and secures substantial compensation for that which is sure to be lost in any other event...

I do not speak of emancipation at once, but of a decision at once to emancipate gradually. Room in South America for colonization, can be obtained cheaply, and in abundance; and when numbers shall be large enough to be company and encouragement for one another, the freed people will not be so reluctant to go. LL 487-90