Lincoln for these people gave them the promise of "internal improvements" and the halting the practice of expansion. James Mitchell, was a mentor and advisor to Abraham Lincoln, he said...
"It may not be out of place to examine the position of the manifest destiny statesmen who are ever laboring to annex -- and to extend the limits of the Republic -- those men are bent on the absorption of Mexico, & Centeral America, and in truth there is no end to their cupidity. Suppose the nation abandoned to their guidance -- and success should crown their efforts -- the jurisdiction of the government extended over the whole South West portion of the North America bringing under our rule the seven millions and a half mixed bloods of Centeral America and Mexico, which when added to our own people of color makes the whole twelve millions persons of mixed blood half-indian, half-spanish, half-white, half-black with all the intermediate crosses of those several races. The question now comes up how shall those people be governed -- how shall they come in -- what shall be their rights -- for rights they must have, either equal right, or restricted rights -- but rights they must have-- What shall those rights be and how shall they be exercised? One class of statesmen say we will enslave them -- this is impossible in this age.
A second class say we will extend equal political rights, and civil franchise and thus remove the difficulties of government -- the majority of the American people will not submit to this -- the spirit of the Anglo-saxon in the nation forbids a legal corruption of blood.
A third say we will change our form of government -- we will centeralize, as the British have done; and then by the power of a restricted franchise -- a privileged ruling class -- and strong military arm -- we will throw iron bands around the several tribes and races governing and ruling the whole by strong external pressure -- the power going down from the head or throne -- and not as with us up from the people -- (this is the dreem of the states in rebellion, and the legitimate effect of the slave institution) To all this the true Republican says you shall not corrupt our republicanism.
Rejecting all these as are shut up to have nothing to do with the land of mixed races -- we should not have annexed Texas -- the act was an act of cupidity and we are reaping the effect in part."