He possessed an uncommon share of that worldly shrewdness which not seldom goes with genuine simplicity of character; and the political experience gathered in the Legislature and in Congress, and in many election campaigns, added to his keen intuitions, had made him as far-sighted a judge of the probable effects of a public man's sayings or doings upon the popular mind, and as accurate a calculator in estimating political chances and forecasting results, as could be found among the party managers in Illinois. And now he perceived keenly the ugly dilemma in which Douglas found himself, between the Dred Scott decision, which declared the right to hold slaves to exist in the Territories by virtue of the Federal Constitution, and his "great principle of popular sovereignty," according to which the people of a Territory, if they saw fit, were to have the right to exclude slavery therefrom. Douglas was twisting and squirming to the best of his ability to avoid the admission that the two were incompatible. The question then presented itself if it would be good policy for Lincoln to force Douglas to a clear expression of his opinion as to whether, the Dred Scott decision notwithstanding, "the people of a Territory could in any lawful way exclude slavery from its limits prior to the formation of a State constitution." Lincoln foresaw and predicted what Douglas would answer: that slavery could not exist in a Territory unless the people desired it and gave it protection by territorial legislation. In an improvised caucus the policy of pressing the interrogatory on Douglas was discussed. Lincoln's friends unanimously advised against it, because the answer foreseen would sufficiently commend Douglas to the people of Illinois to insure his re-election to the Senate. But Lincoln persisted. "I am after larger game," said he. "If Douglas so answers, he can never be President, and the battle of 1860 is worth a hundred of this." The interrogatory was pressed upon Douglas, and Douglas did answer that, no matter what the decision of the Supreme Court might be on the abstract question, the people of a Territory had the lawful means to introduce or exclude slavery by territorial legislation friendly or unfriendly to the institution. Lincoln found it easy to show the absurdity of the proposition that, if slavery were admitted to exist of right in the Territories by virtue of the supreme law, the Federal Constitution, it could be kept out or expelled by an inferior law, one made by a territorial Legislature. Again the judgment of the politicians, having only the nearest object in view, proved correct: Douglas was reelected to the Senate. But Lincoln's judgment proved correct also: Douglas, by resorting to the expedient of his "unfriendly legislation doctrine," forfeited his last chance of becoming President of the United States. He might have hoped to win, by sufficient atonement, his pardon from the South for his opposition to the Lecompton Constitution; but that he taught the people of the Territories a trick by which they could defeat what the proslavery men considered a constitutional right, and that he called that trick lawful, this the slave power would never forgive. The breach between the Southern and the Northern Democracy was thenceforth irremediable and fatal.
The Presidential election of 1860 approached. The struggle in Kansas, and the debates in Congress which accompanied it, and which not unfrequently provoked violent outbursts, continually stirred the popular excitement. Within the Democratic party raged the war of factions. The national Democratic convention met at Charleston on the 23d of April, 1860. After a struggle of ten days between the adherents and the opponents of Douglas, during which the delegates from the cotton States had withdrawn, the convention adjourned without having nominated any candidates, to meet again in Baltimore on the 18th of June. There was no prospect, however, of reconciling the hostile elements. It appeared very probable that the Baltimore convention would nominate Douglas, while the seceding Southern Democrats would set up a candidate of their own, representing extreme proslavery principles.