His amiable personality and handsome appearance caused him to make many friends, but he suffered tragedy in his personal life. As president, he made many divisive decisions which were widely criticized and earned him a reputation as one of the worst presidents in U.S. history. Pierce's popularity in the Northern states declined sharply after he came out in favor of the Kansas–Nebraska Act, replacing the Missouri Compromise (which had been declared unconstitional by the U.S. Supreme Court), and renewing the debate over expanding slavery in the American West. Pierce's credibility was further damaged when several of his diplomats issued the Ostend Manifesto. Historian David Potter concludes that the Ostend Manifesto and the Kansas-Nebraska Act were "the two great calamities of the Franklin Pierce administration.... Both brought down an avalanche of public criticism." More importantly, says Potter, they permanently discredited the Manifest Destiny and "popular sovereignty" as political doctrines.
