James Shields (1806-1879), who served as a Senator for three different states, Illinois, Minnesota, and Missouri, as well as governor of Oregon Territory, once challenged Abraham Lincoln to a duel. In this letter, he criticizes the view that the compromise was a pro-slavery measure.
In June, when Shields wrote this letter, compromise appeared to be dead. Then with unexpected suddenness the outlook abruptly changed. In July 1850, President Taylor died of gastroenteritis, five days after taking part in a Fourth of July ceremony celebrating the building of the still unfinished Washington Monument. Taylor's successor was Millard Fillmore, a 50-year-old New Yorker who was an ardent supporter of compromise.
In Congress leadership passed to Stephen Douglas (1813-1861), a Democratic senator from Illinois. Douglas abandoned Clay's strategy of gathering all issues into a single omnibus bill. Instead, he introduced Clay's proposals one at a time. In this way, he was able to gather support from varying coalitions of Whigs and Democrats on each issue.
I find you fall into a slight error which pervades most of the Northern papers. Clay is not a pro-Slavery man. He is as strongly and certainly as sincerely opposed to the extension of slavery as Col. [Thomas Hart] Benton. The question which divides them, independent of personal views is, whether certain measures which both are for will be passed jointly or severally. You have fallen into a slight mistake on another point. The Compromise Bill is not a pro-Slavery measure. It is opposed most violently by the South, and it will be beat by the South--and not least because they consider it a virtual enactment of the Wilmot provision--as it is--but what will turn up after it is beat God only knows.