The Wilmot Proviso raised the slavery issue in the most direct form, and it played an important part in the Presidential contest of 1848. It was simply a repetition of the clause prohibiting slavery that was put in the ordinance of 1787 by Thomas Jefferson, when the Northwestern Territory was ceded by Virginia to the United States. It was a very embarrassing issue to many Northern Democrats, and to a few Southern Whigs who inclined to prevent slavery extension. General Cass, who was made the candidate for President in 1848, originally declared himself in favor of the Wilmot Proviso, but he learned a year later that no man could maintain his fellowship with the Democratic party under the Polk administration and support the prohibition of slavery in the Territories. When the discussion of candidates for the Presidential contest of 1848 became active, General Cass was addressed on the subject of slavery by A. O. P. Nicholson, of Nashville, Tenn., in which he inquired of Cass whether he was in favor of the acquisition of Mexican territory, and what his views were as to the Wilmot Proviso. General Cass answered, December 24, 1847, in which he declared himself in favor of the acquisition of Mexican territory and against the Wilmot Proviso, on which point he said: “I am strongly impressed with the opinion that a great change has been going on in the public mind upon this subject, in my own as well as others, and that doubts are resolving themselves into convictions that the principle it involves should be kept out of the national Legislature and left to the people of the Confederacy in their respective local governments.” But for this declaration Cass would not have been the Democratic candidate for President in 1848, and that declaration also opened the door for the Van Buren bolt that defeated Cass in the great ambition of his life. In addition to the serious political complications which confronted the Polk administration and threatened the defeat of the Democratic party at its close, the Oregon dispute with England, that had been made one of the chief features of the Polk campaign of 1844, was sensibly adjusted by Secretary of State Buchanan, but in utter disregard of the Democratic declarations and ostentatious professions of the campaign. In that contest the Democrats from every stump declared that the boundary line between Oregon and England must be “54° 40´, or fight”; but when the issue became a question of statesmanship and diplomacy, a treaty was made fixing 49° as the boundary, and thus confessing that the claim of the Democrats in the campaign was made either in ignorance or insincerity.